Sometimes you may want to perform some additional actions to Auto Layout calculations done by UIKit itself.
Example: when you have a UIView that has a maskLayer, you may need to update maskLayer as soon as Auto Layout changes UIView’s frame
// CustomView.m
- (void)layoutSubviews {[super layoutSubviews]; // now you can assume Auto Layout did its job // you can use view’s frame in your calculations CALayer maskLayer = self.maskLayer; maskLayer.bounds = self.bounds; …
}or if you want to take some additional action to Auto Layout in ViewController
- (void)viewDidLayoutSubviews {[super viewDidLayoutSubviews]; // now you can assume all your subviews are positioned/resized correctly self.customView.frame = self.containerView.frame;
}