Swift await works by capturing the context and suspending the execution until the called async method returns. Another thing that works similarly by capturing the surrounding context is an escaping closure. So async-await calls can be imagined as equivalent to escaping closure. Whenever you see a method with async mentally replace that method with a escaping completion handler.
Note: This is a Swift rewrite of the original article published in 2020
The maths required for SwiftUI custom layout reminds me of the days before AutoLayout and the constraints based system. The good thing is that Simple Layout Engine already provides a nice system to handle all the maths involved. To demonstrate I would use build the subset of the demo app from the WWDC session on this topic: Compose custom layouts with SwiftUI.
UnfairLock seems to be causing a lot of confusion for Swift developers. Every once in a while I run across some incorrect implementation that reads like:
About mixing UIScrollView with MTKView. This is the trick I learned from WWDC 2012 Enhancing User Experience with Scroll Views session that talks about mixing UIScrollView with OpenGL. The idea is to simply use the MTKView to render whatever metal content we would like and then use the UIScrollView to provide with the scrolling effect. The benefit of using UIScrollView is that we get exactly the same dragging and bounciness behavior that iOS users expect.