What do setNeedsLayout and layoutIfNeeded each do in UIKit, and when should you call them?
setNeedsLayout schedules layout for the next run loop, layoutIfNeeded runs the pending layout synchronously, right now, layoutSubviews is where the system actually places views, and setNeedsDisplay schedules draw(_:) to run again.
UIKitMultiple choiceBasics
This Auto Layout code is meant to slide a panel up, but the panel jumps into place with…
#layoutifneeded
UIKitMultiple choiceExpert
In one cycle of the main run loop, what's the correct order of the passes UIKit runs to…
#runloop
UIKitShort answerAdvanced
Each cell in a UITableView flash sale list shows a countdown like "Time left 00:12:34"…
#runloop
ConcurrencyShort answerIntro
In a UIKit screen you set label.text = result inside a network response callback, and…
#runloop