Update note: James Goodwill updated this tutorial for Xcode 10 and Swift 4.2. Soheil Azarpour wrote the original post and Richard Turton completed a previous update. Everyone has had the frustrating experience of tapping a button or entering some text in an iOS or Mac app, when all of a sudden: WHAM! The user interface stops responding. On the Mac, your users get to stare at the colorful wheel rot
