It's been a year since SwiftUI was released, and many iOS developers who are lucky to only support the two most current iOS versions will soon be able to start writing SwiftUI in their production apps. There are clear benefits to using SwiftUI (I could probably devote a whole post to them), so the question I've been thinking about is: where to start?

I've been rewriting parts of CIFilter.io in SwiftUI, and one issue I ran into recently was that SwiftUI previews didn't seem to work as advertised. When I opened the preview, it would trigger an app build, eventually show up, but there would always be a banner telling me that previewing had been paused...

I've been working lately on rewriting some of CIFilter.io in SwiftUI. One crash I came across that initially stumped me would happen when resetting my UIHostingController's rootView to a view that was equivalent to the one already set...

Whenever a new major version of Xcode is released, one of the first things I do is download it and run it with the various codebases I'm working on. Usually the new version of Swift is smarter and can surface more warnings and diagnostics, and the Xcode 12 beta release earlier this week (with Swift 5.3) is no exception...

A problem that many people run into after writing enough SwiftUI is how to make it so that two views inside an HStack have equal width, such that if the HStack grows both inner views expand proportionally...

You can nest property wrapers in Swift, but it's difficult. NSHipster has a great article about all things property wrappers, and the summary of trying to compose them (which others have echoed) is that it's hard and prone to compiler errors...

I've been talking a lot online about how useful SwiftUI has been in building debug components for Fluency - debug menus are one of the places where you can start using SwiftUI right now..

Recently, I've been learning more about Metal - I'm still working through the basics, but I've written a couple of posts and tweets about it, and I'm about halfway through Metal By Example. Up until now I've mostly been coding sample projects, but I recently had the opportunity to prototype a Metal implementation integrated into our production app at work...

One of the "Things I Don't Know" in the iOS ecosystem is Metal. As such, I've been working through Metal By Example recently, which still stands as a great introduction to Metal...

In the wild world of 2019 SwiftUI development, lots of things aren't documented. One such thing I ran into recently was the usage of RelativeDateTimeFormatter in a Text view...

I wrote previously about a technique I use in Trestle and CIFilter.io to support iOS 12 and lower while still using system provided, dark-mode accessible colors...

I've encountered this bug enough times that I figured it was time to write a quick post about it. If you've looked into multiple window support for your app in iOS 13, you might know that a lot of the setup you used to have to do in the app delegate now lives in the scene delegate instead...

In this post we'll look at a very specific but tricky interaction in UIKit, one which took me multiple days to work out how to implement. It's two view controllers of different sizes, pushed on a UINavigationController, which is presented as a popover. The view controllers...

For some reason lately, I've been having a lot of trouble installing apps and running tests in the iOS simulator on Xcode 10 (non-beta). The error message looks like this...

At the beginning of June, I launched sfsymbols.com since there wasn't a reference available on the web for searching and filtering the list of 1500+ system icons included in...

At WWDC 2019, Apple announced that Dark Mode would be supported on iOS 13. There are some significant changes to UIKit in order to support this - many of them are detailed in the talk Implementing Dark Mode on iOS which I'd highly recommend watching...

Pop quiz: in a UIButton, how do you set a padding of 10pt between the image and the title? I had to do this at work recently, and I was surprised at how hard it was to reason about. There are several posts talking about this topic (including this one which uses edge insets to flip the title and image!), but the answer for my use case was pretty hard to find...

About a year ago I wrote a puzzle game called Trestle. If you download it using any of the links in this post (by clicking on them on your iOS device), you'll get a nice Easter egg and two of the (normally paid) level sets enabled for free...

Today I'm launching CIFilter.io 🎉 CIFilter.io is a project I've been working on for the last few months, and today it's open source. It has two parts...

For my current side project, I have to export CIFilter parameters to json, and I've been running into issues with various CoreImage types not conforming to Swift's Codable...

At the most recent Swift Language User Group meetup, Patrick Barry presented a great talk about how Lyft implements dependency injection. I'd highly recommend watching the video - I was impressed by how clean and...

After struggling for some time with CIFilter documentation at work, I've been working on an app which can apply filters interactively for various inputs...

I've been working on a side project for better CIFilter documentation lately, and I decided this was as good of a time as any to try out RxSwift. We use reactive programming at work, but I haven't really been able to dig into it yet...

Another MacOS and another struggle through installing nokogiri. Most places online recommend using...

To clear a value from UserDefaults, I previously thought it was fine to do something like this:

UserDefaults.standard.set(nil, forKey: "myKey")

Turns out that this works differently in different iOS versions. Starting in iOS 11, setting nil for a key works as I expected.

There are some times in Swift, like when using System Trace, that you want to get the pointer value of an object directly as a UInt (passing the pointer to kdebug_signpost is one). I was surprised at how hard it was to find documentation on how to get a Swift reference’s pointer value as a UInt.

Swift can be tricky sometimes. For example, what does the following print?

class A: NSObject {
  let x: Int

  init(x: Int) {
    self.x = x
  }
}
func ==(left: A, right: A) -> Bool {
  return left.x == right.x
}
print(A(x: 1) == A(x: 1))
print([A(x: 1)] == [A(x: 1)])