How does your app behave when it's connected to a captive WiFi network that hasn't authenticated yet? This proof of concept code from Felix Krause shows you how to cope with the situation so you can at least let your users know that they're currently captive.
Soroush Khanlou on the process of figuring out where an optimisation was needed, and then picking the best solution for it when trying to get the twenty smallest numbers from a large array. The result is this function, but as always it's the journey that's really interesting.
More open source from Airbnb, this time the collection view layout that powers their main content view. I still love that UICollectionView was architected in a way where the layout is totally independent of the content. We get to take advantage of all of the benefits of a standard collection view without being tied to any single look and feel.
Displaying HTML is easy enough on iOS, but Markdown and LaTeX both require pre-processing to get to HTML. This control from Ahmed Elkady, Orla Mitchell, and Jake Bolam renders any of those formats natively. The inclusion of YouTube/Vimeo support is curious, I'd have been tempted to make that a separate component but Markdown support is certainly useful.