Dan Rosenstark, Author of MIDI Designer, muses about all things tech. Particularly: Notes on software development in Swift, Objective-C, and many non-Apple languages. Also: lots of random technology notes on OS X and iOS.
I don't really understand this Visual Format Language (VFL_ stuff, and it rarely does what I want, but if you read the Apple page on it you'll get the idea.
Anyway, here's an extension to use them in Swift. Substitute UIView for NSView if you're working on iOS
Here is is on SO: link