The Breakroom

Tot 1.5 – Smarter Bullets and Watch Out

October 4, 2022

By Craig Hockenberry

Our last release of Tot introduced a new feature called Smart Bullets. These special bits of text made it easy to create lists where you could check off items. (Check out “What’s New?” in the app help and you’ll get a quick demo.)

One shortcoming with Smart Bullets was that you needed a mouse to manage them. And now with version 1.5, that’s been improved: there are keyboard shortcuts to both add and toggle Smart Bullets. Your hands never have to leave the keyboard!

We’ve also added support for printing out the contents of your dot. In today’s digital world, that seems kind of a weird feature until you realize that it’s a great way to create a quick PDF for email or to print a one-off shipping label.

Folks on iOS 16 will also be able to take advantage of the new system Find & Replace when editing text. After selecting some text, you’ll find “Find Selection” in the Edit menu. “Find” is also available if there is no selection. If you want to replace text or use other options, tap the magnifying glass menu.

There are also some user interface improvements. If you have aging eyes (/me raises hand) then the adjustable line height in the Format menu (macOS) or Settings (iOS) will be a welcome addition. We’ve also heard your customer feedback and made Tot’s menu bar icon a standard size and appearance. There’s even a new icon that matches the watchOS app.

Your menu bar is getting a new look, and there’s’ a new “Dot” app icon available.

Hello Tot Mini

Wait a second: watchOS app?

Yes, you can now tote Tot around on your wrist. It’s surprisingly handy: one of our beta testers is a distance runner and uses a dot for directions. Shopping lists and other kinds of reminders are also a natural fit.

In addition to viewing your text, you can also make simple additions with dictation or the Scribble keyboard. Full editing on the watch isn’t feasible, but it’s great to be able to quickly get a random thought into a dot and having it sync back to your phone or desktop!

Tot Mini is a watchOS 9 app and available to download as a separate purchase on the App Store. To learn more about Tot, check out the product website. Full details about this and other Tot releases is available in our version history.

Enchant Your Inktober with Linea Sketch

September 28, 2022

By Webmaster

October returns once again with an orange armful of pumpkin spice, a crisp autumn breeze, and a way to channel our creativity every day of the month. Inktober encourages artists, both amateur and professional alike, to pick up pen and pencil and express themselves by crafting a drawing each day based on the official list of prompts.

The official list of drawing prompts for Inktober 2022

For the past three years we’ve contributed to the cause by creating a set of handy templates for Linea Sketch that outlines the prompts for each of the 31 days in Inktober. This year’s list of templates is once again ready for download and broken out by page numbers that contain the prompt for that day’s drawing. The templates are perfect for those who like to have a uniform set of sketches for the entire month or who want to stay tight and focused on their daily creations.

As always, Linea’s Inktober 2022 templates are completely free, easy to set up, and should quickly get you on your way to joining in on the inking fun. Last year we created a short video tutorial on how to get the templates into Linea Sketch for the iPad that will help guide you through the process this year as well. Be sure to check it out

Lastly, don’t forget to tag your posts with #LineaSketch – we always share our favorite drawings over on Linea’s Instagram so it’s a great way to step into the lime light! Apply new screen protectors and charge those Apple Pencils because October will be here before you know it!

Wallaroo and SwiftUI (5 of 5)

September 23, 2022

By Sean Heber

We were getting near the end of Wallaroo development and the app was close to fully functional, but as mentioned at the tail of the previous post, there was still one more important thing that I had to figure out how to implement.

The wallpaper detail view has a popup with metadata about the wallpaper you are viewing. Some of that metadata takes the form of tags and tapping a tag needed to push a new page on the navigation stack.

Normally this would be relatively easily done with a NavigationLink but there was a wrinkle: The button that needed to have these links lived inside of a .popover which, when presented, is not part of the navigation stack! That resulted in the NavigationLink being disabled since from its point of view there was no navigation stack to push anything to.

Wallaroo’s tags let users quickly find similar content across the entire app

Luckily Apple introduced NavigationPath this year and it seemed like it might be possible to use it to solve this problem.

Of course since NavigationPath was a brand new API, there wasn’t a lot of information out there about how to work with it. Many of the quick “tutorial” posts that showed up within hours of the WWDC announcement didn’t help, either. (Unfortunately most were nothing more than reprints of Apple’s simple demonstration code which was immensely unhelpful.)

Those that went farther did things like tuck the NavigationPath into an ObserverableObject which was then added to the environment or passed explicitly to subviews for them to manipulate. I’m certainly not a SwiftUI style expert, but that didn’t feel right to me.

Fueled by my prior research into finding the “right” way to pass what I needed around for the parallax effect, I opted to model a solution based on the way that dismiss and openURL are implemented in SwiftUI itself: As an environment action.

Instead of passing an object around that was nothing more than a thin wrapper of the navigation path, I created an action struct that implemented callAsFunction() just as Apple does with DismissAction, OpenURLAction, RefreshAction and others. The root view then added the action to the environment so all child views could use it.

With this approach, the NavigationPath is private to the root view which remains in control of adding things to the path. The root view also already implemented .navigationDestination for the views in the navigation stack, so it made sense to me that it should own how pages get pushed, too.

When the detail view needs to open a new gallery page, it uses my new OpenPageAction from the environment to request the new page much like this: openPage(.gallery(.tag("abstract"))).

We also sometimes needed to present other standard views that were overlays of the whole UI (like the purchase screen) and all I needed to do was add a case to the Page enum and a new line to the function that opens the pages. The same mechanism that pushes a new view on the navigation stack can also now open a new modal popup without the caller needing to know the difference.

(Note: When the first iOS 16.1 beta dropped, we suddenly had a navigation regression where sometimes empty views were pushed on the navigation stack. I spent an afternoon and isolated a simple reproducible example [filed: FB11518877]. We reached out to multiple Apple engineers that we had contact with and eventually learned this is a known regression which is expected to be fixed before 16.1 ships. I implemented a workaround in the meantime – but fingers crossed!)

The last bit of polish we wanted before shipping was to make the favorite button do something a bit more fun when you pressed it.

Visual flourishes like the Favorite Heart animation add joy and tactility to Wallaroo

Gedeon hand drew a wonderful animation frame by frame as a reference and I set about trying to figure out how to make it work.

My first instinct was that this should exist as a custom view transition, but I spent a lot of time trying to figure out how to make that work and couldn’t get it right. I suspect I was missing something obvious, but I was running out of time and couldn’t spend any more time digging into it so I needed a different way.

I was also torn between deciding if I should find a way to translate all of the frames of Gedeon’s animation to code or just use the images he had already made and be done with it.

Given enough time I could have probably worked out a way to actually draw each of the shapes into an animated Canvas, but ultimately I gave up on that and built a flip book-style animation view powered by TimelineView to play a sequence of Image views.

I set up the flip book animation to play when it first appeared and then to update a binding when it was done which allowed me to overlay it on top of the normal heart button, play when it appeared, and then have it disappear when finished. I think it turned out pretty great!

Building Wallaroo in SwiftUI was quite an eye-opening experience for all of us. There were a lot of unexpected troubles along the way, but we worked through them and found solutions. There were certainly some problems that, in my opinion, would simply have never occurred had we built the app with UIKit – but that said, I’m not sure we would have completed the app in time for the launch of iOS 16 without SwiftUI.

While I ran into a lot difficulties that may or may not be bugs and spent a bunch of time trying to better understand the “right way” to do things for future reference, Craig was able to easily implement the entire set of settings screens, the purchasing flows, Patreon integration, and a bunch of other simple but important views without any significant problems – likely because they all better fit the types of things that SwiftUI was originally designed for in the first place.

In my opinion, a lot of the app’s ancillary views would have required far more code and time to build with UIKit and that’s an important point in favor of SwiftUI despite the occasional trouble in some corners.

I think it’s important to remember that our goal was to build an entire app which means dealing with a lot of the incidental stuff that SwiftUI makes trivial – like experimenting with different interactions, layouts, animations, and even whole view hierarchies. Making quick changes to those things in SwiftUI requires practically no code and absolutely no auto layout constraints, no management of delegates or controllers, and no subclassing all while adapting to different aspect ratios and accessibility settings with nearly no effort. (Plus you can see the changes as you type them if you have the previews set up!)

Clearly there are some blindspots in the framework that need to be addressed, but without trying to use it we could not have known where they were. Just because some parts of the app may have been less troublesome to implement had we used UIKit doesn’t mean SwiftUI itself is a failure or useless. Our new experience will hopefully allow us (and perhaps you) to better pick battles going forward. There’s no rule against using UIKit when necessary, after all – but ideally (in my opinion) we shouldn’t have to.

I hope you enjoyed this deep dive into the Wallaroo development process. For my part, I mostly liked working with SwiftUI once I started to get used to the way it works. There were certainly some points of deep frustration along the way, but in my experience that happens in every single project no matter what technologies are being used to develop it (yes, even UIKit). Unfortunately there will always be things that just don’t seem to work as well as you’d hoped. Maybe someday someone will create the one true holy grail of app development frameworks, but until then, we might as well play with what we’ve got.

Get Wallaroo from the App Store!

Wallaroo and SwiftUI (4 of 5)

September 22, 2022

By Sean Heber

In the last post, I talked about overcoming some issues with Wallaroo‘s main gallery view, but unexpectedly even the simple wallpaper detail screen held its share of challenges!

The biggest surprise for me was how much trouble I had implementing the paging view to swipe left and right between wallpaper variants. In UIKit it’s trivial to enable paged mode on a UIScrollView to get this behavior, but I couldn’t find a way to do it in SwiftUI for some reason. I ran across a bunch of tutorials that were manually implementing panning gestures and paging and I was flabbergasted. Did I really need to do all of this myself from scratch?

I tried a few different open source paging view implementations I found on GitHub but they were all lacking in one way or another.

The most glaring problem with them tended to be that the scrolling physics felt entirely wrong. The swipes didn’t have the same momentum that Apple uses everywhere else and the resistance on the rubber band effect (if it even had it) was never quite right. I started going down the road of adapting one of the better ones with more correct physics after I discovered this gem of a project which meticulously deconstructed the formulas necessary to get an Apple-like scroll view feeling. Still, though, nothing about this approach felt right.

Eventually I decided that maybe I should just wrap a UIScrollView to accomplish what we needed and started to dive into that.

I was pretty far into this when I accidentally stumbled across a Stack Overflow comment noting that SwiftUI actually does have a native paging view – it’s just cleverly hidden as a TabView style!



I wasted most of a week on approaches to this before I managed to discover that, lo and behold, SwiftUI actually does have a way to do it – and it’s a single line of code: .tabViewStyle(.page).

I was supremely pissed off at myself for somehow missing this. Despite all of my searching, I never managed to notice any reference to it in the documentation and apparently didn’t remember anything about it from any of the WWDC videos I had watched, either. I suppose perhaps my search terms were too laced with an assumption that it’d be a part of ScrollView somehow or that it would exist as its own view?

I soon learned that SwiftUI didn’t always include support for a paging view – which is why there were so many outdated tutorials and open source projects out there for me to accidentally find instead of the official API. Argh.

SwiftUI changes so much every year and I can’t count the number of times I found an accepted Stack Overflow answer for a thing that was completely wrong as a result. (This is also true of Swift itself – although it’s getting better over time as they’ve become more resistant to source breaking changes.)

There’s also something off about how SwiftUI documentation is written and organized. It frequently feels next to impossible to find the name of whatever view modifier you might be needing unless you more or less already know what you’re looking for. To make matters worse, the fact that SwiftUI’s view modifiers almost all exist as function extensions on View means just pressing the period key and browsing autocompletion suggestions tells you nothing about what might or might not make sense to use in your current context.

The plethora of tutorials, Medium articles, YouTube videos, and books also mostly have a feeling of “magical thinking” to them – as if you just need to memorize incantations to spells rather than learn any of the actual science behind the effects you are trying to achieve. I find that aspect of the SwiftUI ecosystem extremely frustrating and disappointing.

All together these things make SwiftUI feel very difficult to learn and master.

So anyway, after discovering TabView‘s support for paging, I threw away everything I had been working on for a week and used it instead.

Unfortunately it is extremely buggy.

I don’t want to get in to every single problem I ran into with it or this blog series would be about three times longer than it is already, but suffice to say there were a lot. My source file has 6 different bullet points of issues I ran into!

Luckily I was able to workaround them all (one dumb issue was needing to wrap the TabView inside of a ScrollView with scrolling disabled in order to get it to stop jumping around when it first appeared which then of course ended up requiring a second workaround to fix an issue with that workaround…), but the worst, by far, was a memory leak/retain cycle!

We discovered the memory problem around the time I was working on the AsyncImage replacement I mentioned earlier. I had implemented various caching schemes for the images and I kept modifying my approach because it turned out the app was eating RAM and the most obvious culprit was the cache. In fact the initial reason I ripped most of the caching out and revisited it was in an attempt to hunt down this leak!

Unfortunately even with all caching removed I was still seeing a huge memory leak somewhere. I tried using Instruments to find it, but I had no luck deciphering where it was coming from – other than to see confirmation that memory was indeed leaking like crazy.

“Be a software developer,” they said.

I spent two days on this problem.

I don’t mean two work days – I mean pretty much two entire days stopping only for food and sleep.

I was trying everything I could think of to narrow it down. I first started by commenting out random stuff and manually running through the very long sequence of events I had found that could reliably consume the memory. Over… and over…. and over… (And over and over and over…)

Eventually I discovered (around 1am on the second day) that using a selection binding on the TabView was keeping the entire TabView instance alive somehow even when the view that contained it was destroyed.

So over time, after viewing a bunch of wallpapers and scrolling through the variants, all of those huge images were staying in memory even when you went back to the gallery view and loaded a different wallpaper! Slowly, with regular usage, the consumed memory climbed and climbed until iOS killed the app.

My paging view was its own standalone view that had a TabView inside of it. To expose the currently selected tab to the wallpaper details view, I passed in a binding which was in turn used by the TabView. Somehow, though, this is what was causing the problem because when I commented that part out, it wouldn’t leak – but I needed the selection binding to be passed along from the detail view to the inner TabView somehow!

On a whim I tried doing something more indirect and added a new state variable to the paging view which would hold the selection and passed that to the TabView as a binding instead. Then I used .onChanged to note when the selection state variable changed and updated the original binding that was passed into my wrapper view from outside. This appeared to break whatever retain cycle was happening.

I don’t know exactly why this worked (I can only speculate), but some part of my tired and sleepy brain thought to try it and it turned out to solve the issue in the end – but not without some pretty serious frustration and anger.

I feel like I should send Apple a bill for the pain and suffering I endured on this one.

Since this caused me so many problems, I decided that I would share my PagingView code to maybe save someone else some time or see if anyone has any better ideas. (And if we’re really lucky, maybe a SwiftUI engineer will see this and fix it!)

Now that this rather unexpected battle with the paging view was behind us, we were surely on the homestretch! Wallaroo was nearly fully functional – except for one minor detail

Wallaroo and SwiftUI (3 of 5)

September 21, 2022

By Sean Heber

Now that Wallaroo had a unique and good-looking main gallery view along with nice parallax and blurs and everything, my focus shifted to optimizing scrolling performance.

The parallax and lazy custom layout seemed to perform just fine, but rendering the glyphs/buttons on each tile view as well as the actual wallpaper image seemed to be slowing things down a lot.

When I commented each of these bits of code out in turn, scrolling would become silky smooth, but enabling just the glyph/button overlays or just the wallpaper images would result in unacceptable stuttering on my 2016 iPad Pro. Hmm!

Slow and steady might work for races against rabbits, but it’s a drag during user interactions.

Eagle-eyed readers might have noticed earlier that I said I was using AsyncImage “at the time.” Eventually I replaced it with a custom implementation on my quest to achieve smoother scrolling and then extended it a bit more to solve another problem we ran into.

It seemed (at least on the earlier iOS 16 betas), that AsyncImage did not prepare the image for display before rendering it. That meant that when two or three images all loaded during the same view update cycle it would cause animation hitches.

I solved this in my custom view by using a .task modifier so I could async load the image data myself, then convert it to a UIImage, and then call the async version of UIImage.byPreparingForDisplay all before finally assigning the SwiftUI Image instance that would ultimately be displayed to a state variable.

Around this time Craig also realized that as I worked throughout the day my computer was hitting the image server a whole lot and this probably was not going to scale very well once it went live in the App Store.

To address this, I adjusted the URLRequest for the images to always return from the URL cache directly when possible, but ultimately we fixed our server to set the correct HTTP caching headers so the URL loading system stopped rechecking for freshness all the time and trusted that the cached data was good.

If Craig hadn’t been watching our server logs at the time, I’m betting we’d have totally missed this and then had to deal with a flood of server traffic on launch day!

(Aside: It may sound like we arrived at all of this in a matter or hours, but of course we didn’t. I spent a ridiculous amount of time off and on over weeks trying various caching schemes for my custom AsyncImage that prepared the image in different ways, kept the prepared image around keyed by URL, used NSCache or a simple Dictionary, used a Swift actor, etc. Happily I was able to get rid of all of that complication once the required pieces finally fell into place. This sort of thing happens a lot and I often spend a bunch of time on things that turn out to be dead ends. I tend not to stop the moment I get something working, but instead keep thinking about it for a while trying to simplify or get rid of as much code as I can. Sometimes the results are good as in this case, but other times it can go badly where stuff becomes much too specific to a single situation and ends up causing problems for myself later. Such is the nature of evolution, I guess?)

Another of the limitations of AsyncImage that I was able to work around in our custom implementation is that AsyncImage only delivers the final Image after the load finishes and not the original data.

We wanted to be able to access the raw downloaded data of the big images as seen in the full wallpaper detail view so we’d have it when saving or setting the wallpaper. I built a way into my custom image view to get the downloaded image’s raw Data as well as the prepared Image to avoid needing to re-encode the image or download it again separately. There are other ways to solve this problem (I tried a few), but it seemed the most straightforward to do it this way since it ensured the image data was only ever downloaded once.

After getting the thumbnails to load without a hitch, I moved on to the troublesome issue with the glyphs.

There are at most three symbols on each wallpaper gallery tile: The favorite heart, the multi-variant indicator, and the lock (which only shows up on some of them when unsubscribed). When these overlays were enabled, it caused a ridiculous amount of stuttering.

I had a suspicion as to the root cause: Gedeon had wanted the glyphs to be rendered with a custom shadow using a blend mode that didn’t interfere with the semi-transparent favorite heart but also worked against a wide range of wallpapers. This effect was first implemented early in the prototyping stage and hadn’t been revisited.

Wallaroo’s drop shadows use a custom setup so they look good in all states (semi transparent and fully opaque) and against a wide array of backgrounds.

Sure enough when I disabled these effects the scrolling was perfectly smooth. I tried a whole bunch of things to get this to perform better until finally stumbling on the fact that I was using a .mask modifier on the glyph views in order to get the appearance we wanted. When I came up with a much smarter way to make the effect work without masking, the performance skyrocketed. I guess the lesson here is: Don’t use view masking if you can help it!

This highlights one of the weakness of SwiftUI. It is very hard to debug this sort of thing or to get a sense of where time is being spent by the engine because so much of it is inaccessible and outside of our control. Hopefully these things can be improved somehow in the future. For all I know, maybe there are already ways to use instruments to diagnose problems like this – although personally I find a lot of the instruments to be inscrutable and it ends up taking me just as long to trace through a problem with them as it does to hunt around with educated trial and error. But maybe that’s just me.

With most of the issues surrounding the main gallery view taken care of, it was time to finally move on to the much more straightforward wallpaper detail view! How hard can it be?

Wallaroo and SwiftUI (2 of 5)

September 20, 2022

By Sean Heber

At the end of the previous post of this series, Gedeon had just suggested that we add a parallax effect while scrolling through Wallaroo‘s gallery view.

There’s nothing inherently complicated about parallax – it’s just moving a background layer at a different rate from the foreground. The real question was how the heck I was going to do add it without ruining the simplicity of the code I had built so far.

After I stopped despairing, I realized I already had the information I needed to do this: I knew where the frame of the overall visible view was on screen, and I knew the frame of the child tile view. That’s all it takes to come up with some kind of an offset for a layer. The problem was, that information wasn’t really where I wanted it to be – namely somewhere inside of the ReleaseTileView.

I started by trying to compute an offset in the main content view and passing it into the ReleaseTileView, but that didn’t feel like a very “SwiftUI” way to do it (although it worked and was relatively straightforward). Instead, I spent some time trying to research how problems like this are meant to be solved in a way that doesn’t fight (or at least publicly embarrass) the framework.

Some of the scenarios I thought about where things like: What if I wanted to have this parallax effect in some small cutout deep inside of the tile view and not on the whole background? How would the information get all the way there? Would it be passed from view to view in their initializers? What if Gedeon suddenly decided that only some of the views should do the parallax effect while others should not? What if that condition was something specific to an individual release? Etc. While some of these weren’t likely scenarios, I wanted to make sure I did it “right” at least insomuch as I could determine what that meant.

The parallax effect adds subtle depth to the UI. Watch Kirby’s clouds change as he scrolls by!

What I ended up going with was pretty simple: I decided that knowing where the containing gallery’s frame was would likely make sense as an environment value, and so I added the visibleGalleryFrame that was computed in the code snippet in part 1 as an environment value for all of the child tile views to use. To get the parallax to work, the tile views measure the frame of whatever area they want to apply the parallax effect to and compare it with the environment’s gallery frame and offset things accordingly.

While I’m sure there are many good ways to do it, it seemed to me that this approach is in line with how SwiftUI wants us to think which is to consider which pieces of information are part of something like the “world” that a view lives within vs. the information a view is meant to be displaying.

Of course, even this is still a bit fuzzy. I think it could be argued, for example, that putting the wallpaper object itself in the environment rather than passing it to the initializer for each child view could also make sense! I’m not sure where to draw the line with this sort of thinking, to be honest. There’s really nothing stopping almost every value normally passed as a parameter from being passed in the environment instead, but there’s something about that which feels like it’s terribly wrong – I just can’t articulate exactly what the rules should be.

It feels like the only thing preventing people from using the environment more often (and perhaps “incorrectly”) is the fact that defining a new environment value involves a bunch of boilerplate in an EnvironmentValues extension! It doesn’t seem ideal to only depend on that friction to guide behavior, though, especially since I’d love to see some kind of new Swift syntax or feature that could eventually make the boilerplate go away!

While the sweet parallax effect was a nice touch, there was still an annoying flaw with the gallery view that jumped out every time we scrolled it: The thumbnails sometimes took awhile to arrive over the network leaving an empty hole while loading.

From my time playing around with Mastodon, I remembered that they had a solution to this which displayed a blurred image while the full thumbnails loaded. I didn’t know how that worked, so I dug into their code a bit to find out how they did it. I discovered that some very smart people came up with a way to encode a blur into a relatively small string using math I do not even remotely understand myself.

Blur hashes create a “soft loading” effect as thumbnails scroll into view.

I shoehorned the open source BlurHash code into a SwiftUI view that could take a hash string and a size and generate an Image from it. Once that was working, Craig modified our backend to compute real hashes for all of the thumbnails and images and included them with the catalog of JSON data that the app downloads when fetching new content. The whole process was surprisingly straightforward and, in our opinions anyway, is much nicer than having a static bundled placeholder image!

Adding all of these bells and whistles makes the app look pretty, but does it perform well? Wait until part 3 to find out – or just download the app and check it out yourself!

Wallaroo and SwiftUI (1 of 5)

September 19, 2022

By Sean Heber

The Iconfactory has been releasing beautiful wallpapers on Patreon for years. Our latest app, Wallaroo, was built to make the process of browsing and using these hundreds of wallpapers more fun and convenient for everyone.

Wallaroo is the first app we’ve built entirely with SwiftUI, so in this series of more technical posts, I want to talk about some specific issues we ran into along with how we solved them. In a separate post, Craig discusses development of the whole app so if you prefer to get a bird’s eye view of Wallaroo’s creation, be sure to check his article out.

Over two months of development, all of us at the factory worked on the app in our own ways. Craig and I did the programming while the designers remastered a ton of their artwork, mocked up UIs, made marketing materials, filled out spreadsheets with metadata, and did all of the other little things that needed doing that us programmers like to pretend don’t exist.

Craig built the entire server backend (where the metadata and images live) as well as Wallaroo’s settings and StoreKit 2 purchasing flow while I worked exclusively on the primary functionality of the frontend. (Now that I write it out I suddenly feel like a total slacker…)

One thing that worried me about adopting SwiftUI was that the demos from WWDC and elsewhere always seemed so superficial. While they usually have pretty animations and relatively few lines of code, most of the apps felt like nothing more than a thin wrapper around a list view. As someone who has done battle with UIKit for over a decade, I know how often a seemingly simple thing can turn out to be ridiculously complicated in practice. Given this, I really had no sense for how SwiftUI might fare when faced with real-world complications.

Since Wallaroo wasn’t designed to be a particularly complex app, it seemed like the perfect time to find out by taking the SwiftUI plunge.

Early Wallaroo gallery concept by Talos Tsui.

The mockup that Talos did of what would become the main Wallaroo gallery view had each wallpaper release being presented in one of four different-sized randomly selected tiles. From what little I knew of SwiftUI, I suspected this was going to be tricky because the framework didn’t (and still doesn’t) have even a simple flow layout, let alone something complicated like a flowing irregular grid! Luckily WWDC22 had just announced the new Layout protocol for SwiftUI, so I hoped I’d be able to use it to make this work. Nothing else about the UI mockups seemed especially unusual or beyond SwiftUI demos I had seen before, but the layout we wanted was something new. So I started there.

Considering that the only SwiftUI work I had done prior to building Wallaroo were some simple toy views over a weekend, it felt a bit like jumping into the deep end to immediately start work on a custom layout – but it turned out to not be too bad! The first decision I made was to avoid trying to implement a “perfect” layout and just get it working for the cases we needed. This meant mostly ignoring infinite and zero size proposals and disregarding the preferences of the children. (I’m sure all the kids out there can relate.)

One of the more interesting things about the grid is how we wanted to randomize the shapes of each child view to keep the gallery fresh and visually call attention (by way of size) to different wallpapers over time as the list of releases changed. I didn’t want to have to somehow assign a “shape” to each child view from outside of the layout, so I tried to find a way to get this logic inside of it so it could be automatic.

What I came up with was to seed a random number generator with the number of subviews that the layout received. This ensured that the layout would be consistent as long as the wallpaper list didn’t change – which is what we wanted. I then used that random number generator to shuffle a bag of shapes (large, vertical, horizontal, and small) and pulled the next one whenever processing the next subview. If the pulled shape would fit in the remaining horizontal space, I used it. If it didn’t fit, I’d discard it and try again. When the bag was empty, I’d fill it back up with a couple of sets of shapes, shuffle it, and keep going. I think it worked remarkably well! (Incidentally I used a similar technique to randomize Frenzic: Overtime’s daily challenges by seeding the random number generator with Game Center’s current leaderboard date.)

We were a few days into this, and I was feeling pretty good about it when the first real-world complication reared its ugly head: Custom SwiftUI layouts aren’t lazy!

The Captain Pike Appreciation App. Anson Mount knows how to hit it.

This became distressingly apparent when I replaced the one bundled test image I was using for each of my tiles (a wonderful portrait that Dave did of Captain Pike from Star Trek: Strange New Worlds) with URLs for images on our server.

Suddenly whenever the app launched or the gallery came back into view, all 15 or so test images would start downloading immediately even if they were well off the screen – which obviously wasn’t going to scale. This happened because AsyncImage (which I was using at the time) starts loading when the view pops into existence in the view hierarchy and not when the view actually becomes “visible” on screen. Doh.

What I needed to solve this was some way to discern if the view was actually on screen or not and then emit the appropriate view. Since I had already put the GalleryView inside of a ScrollView in order to scroll, it turned out to be easy to capture a rectangle that could be used to indicate the “on screen” frame by simply putting the ScrollView itself inside of a GeometryReader.

The next step was to figure out where on screen the child views were actually being placed. This was easily accomplished by putting each of the children of the layout inside their own GeometryReader, too.

So now I had two rectangles in global coordinates – one for the container frame, and one for the frame of the child view. After that it was just a matter of checking if those rectangles intersected or not and either emit or not emit the tile view. SwiftUI’s ViewBuilder has no problem with this – it worked great. Now all of the child views would only exist when actually on the screen and cease to exist when they left it. This allowed for images to be lazy loaded as you scrolled without any child views needing to worry about the details.

I think laziness for custom layouts ought to be built into SwiftUI, but at least my code for adding it turned out to be relatively simple in our case:

GeometryReader { galleryGeometry in
    ScrollView {
        let visibleGalleryFrame = visibleFrame(for: galleryGeometry)
        GalleryLayout(columns: visibleColumns(for: galleryGeometry.size), padding: 20) {
            ForEach(releases) { release in
                GeometryReader { cellGeometry in
                    if visibleGalleryFrame.intersects(visibleFrame(for: cellGeometry)) {
                        ReleaseTileView(release: release)

(Note: The visibleFrame(for:) function just expands the safe area the geometry proxy includes so that the returned CGRect is the actually visible space and not just the safe area space.)

By this point things were looking and working pretty well for an early prototype – the primary stuff we were worried about being able to build in SwiftUI seemed to be solved! I was about to move on to other parts of the app when Gedeon said, “Hey, can we add some parallax when scrolling?”

Actual photo of Sean’s reaction when Gedeon suggested adding parallax.

What’s New? Wallaroo!

September 12, 2022

By Webmaster

Introducing Wallaroo – the quickest and easiest way to browse and set wallpapers on your iOS devices. The Iconfactory has been crafting custom wallpapers for the Mac and iOS community for over 25 years, and now we’ve packaged them up in a fun, handy app that’s available today on the iOS App Store.

Wallaroo comes with dozens of FREE wallpapers with hundreds more available after you subscribe. New wallpapers are released each week so there’s always something to fit your mood or current style.

It’s also fun to say!

Quick and Easy

Wallaroo’s superpower comes to you thanks to Apple’s Shortcuts. A series of simple actions takes the drudgery out of getting something onto your Lock or Home Screen. Pick a wallpaper in the app, tap a button, and you’re set!

Our wallpapers are organized into collections like Abstract, Comics, Dark Mode, and more. Every wallpaper release also has tags that let you explore and find related content. And when you find a wallpaper you love, it’s easy to make it a favorite for future reference.

Latest and Greatest

For the past three years, our Patreon supporters have enjoyed regular, weekly wallpaper updates so there’s always something new on the horizon. Wallaroo continues this tradition with new and exclusive content each and every week, so the next great wallpaper is never more than just a few days away.

Set It With Style

We’ve always been inspired by popular culture for as long as we can remember. Wallpapers that pay homage to movies, anime, television, or the latest technology are just some of the fun topics to explore in Wallaroo’s galleries. We also love beautiful, abstract, and elegant wallpapers so naturally Wallaroo has plenty of those to offer as well.

Many releases also come with additional colors and layouts for that added touch of customization you’ve come to expect from the Iconfactory. There’s something for everyone in Wallaroo.

No Ads, Only Wallpapers

We’ve thrived over the years by treating our customers with respect. Wallaroo doesn’t collect your information, serve you ads, or push sketchy schemes. We just want to keep bringing you great content and get paid for our efforts. It’s as simple as that.

Give Wallaroo a Go!

Wallaroo is available today as a FREE download on the iOS App Store. Be sure to visit the official product website and follow us on Twitter for more information in the days and weeks ahead. If you love customizing your screens, hop on over and give Wallaroo a go!

Tot & xScope Back to School Sale

August 17, 2022

By Webmaster

Now through August 31st, we’re offering a 30% discount on two of our most popular productivity tools – Tot for note takers and xScope for designers and developers.

Saving a bit of cash is always welcome, even if you’re not a student, so be sure to head to the App Store to pick up Tot Pocket at a reduced price or use the promo code BACKTOSCHOOL when you purchase xScope from our website. Don’t wait, this sale will be over before you know it!

Gaming the System

August 1, 2022

By Webmaster

Those industrious bots are back with an update to our fast-paced puzzler, Frenzic: Overtime. Whizbot’s Test Lab Daily Challenge has received an upgrade to include all new exciting bonuses and strategies as you compete to be the top bot world wide. The Test Lab now also makes it easier to see the players immediately above and below your current rank on the leaderboard, and the bonus meter is personalized by displaying your player avatar from Game Center.

Finally, for those who want to kick back and build power cores at a bit more of a leisurely pace, Frenzic now offers the ability to toggle between Quick Pace and Casual Pace via Settings. Casual Pace means slower chip and shift timers as well as a less aggressive Cipher on Hacker Levels. Just don’t tell BossBot!

Head on over to Apple Arcade and enjoy the latest update to Frenzic: Overtime today!