Backwards compatibility for iOS 13 system colors

June 8, 2019

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...

UIButton: Padding Between Image and Text

May 5, 2019

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...

Passing data through the App Store with UIPasteboard

April 14, 2019

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...

CIFilter.io (Core Image Filter Reference)

March 30, 2019

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...

CIVector Codable

March 4, 2019

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...

Dead Simple Dependency Injection in Swift

February 14, 2019

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...

iOS Color Wheel Using CIFilter

January 27, 2019

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...

RxSwift: Multiple subscribers for a unit of work

December 7, 2018

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...

Installing Nokogiri from a Gemfile on Mojave

November 13, 2018

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

How NOT to set nil in UserDefaults

October 21, 2018

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.

Casting a pointer to UInt in Swift

October 15, 2018

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.

NSObject Equality is Tricky

November 12, 2016

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)])