turing complete with a stack of 0xdeadbeef
In JavaScript, this pattern is called an Immediately Invoked Function Expression (IIFE) or a Self-Executing Anonymous Function. Swift doesn’t have an “official” name for this, but IIFE works as well as “immediately executed anonymous closure” or “self-executing anonymous closure”. (Thanks to folks on Twitter for helping with this.)
Swift’s strict initialization rules are great. They help prevent an entire category of bugs that were especially common in Objective-C. However, when working with Objective-C frameworks, particularly UIKit, these rules can be frustrating.
Today I am deprecating my open source library, JSQDataSourcesKit. I have already marked the CocoaPod as deprecated and archived the repo on GitHub. I will not be taking additional contributions.
For an iOS project that I am currently working on, I am implementing Dark Mode. The codebase is approaching 7 years old, it is mostly Swift with some legacy Objective-C, and it currently supports iOS 11 and above. Aside from the tedium of ensuring the updated colors are being used throughout the codebase, I expected this task to be straight-forward. However, there were some unanticipated issues.
I recently needed to determine when the user has manually switched between dark mode and light mode on macOS. In my menu bar app, Lucifer, the icon reflects the current appearance setting when you change it from the app — an inverted pentagram for dark mode and an upright pentagram for light mode. But there’s a bug. If the user manually changes the appearance setting from System Preferences, or if they are using the new “auto” setting in macOS Catalina, the icon gets stuck in its previous state.
This isn’t complicated, but I found it confusing. Perhaps I am spoiled by the more modern APIs in UIKit. When writing Lucifer, a menu bar app, I wanted to have different actions for left-clicking and right-clicking on the button in the menu bar. To my surprise, this was much more cumbersome than I expected.
A few weeks ago, I spoke at Realm in San Francisco at the Swift Language User Group (#SLUG) meetup. A video of the talk is now online over at Realm’s blog, where it is synced with my slides. If you haven’t already seen it, go check it out!
In iOS development, the core of nearly every app rests on the foundations provided by UICollectionView and UITableView. These APIs make it simple to build interfaces that display the data in our app, and allow us to easily interact with those data. Because they are so frequently used, it makes sense to optimize and refine how we use them — to reduce the boilerplate involved in setting them up, to make them testable, and more. With Swift, we have new ways with which we can approach these APIs and reimagine how we use them to build apps.
Surprisingly, I have not seen anyone talking about what I just discovered in the iOS 9.0 API Diffs. (Well, actually what Max von Webel discovered.) There’s a hidden gem in the UIKit diffs. We no longer have to suffer through tracking down obscure bugs due to non-zeroing weak references.