Say, I'm building a custom UISegmentedControl by laying out several buttons and describing their states. I am attaching TouchUpInside listeners to them in order to change their appearance accordingly, when selected. The problem is that I don't know where to remove these listeners in order to avoid a memory leak. UIView and UIControl don't have ViewDidDisappear like UIViewController which I'm using to remove listeners when it becomes invisible.
Where should I remove these listeners?
I would suggest looking at when the following are called, and see if they suit your needs for UIView:
didAddSubview:, willRemoveSubview: Implement these methods as needed to track the additions and removals of subviews. willMoveToSuperview:, didMoveToSuperview Implement these methods as needed to track the movement of the current view in your view hierarchy.
willMoveToWindow:, didMoveToWindow Implement these methods as needed to track the movement of your view to a different window.
(Above taken from this SO post: SO Reply)
This would allow you to follow what the 'superview' is doing with the view, and when it's being dismissed you should be able to run your clean up code.
You don't need to remove your "listeners". UIControl doesn't hold strong references to targets - from the documentation for addTarget(_: action: for:):
The control does not retain the object in the target parameter. It is your responsibility to maintain a strong reference to the target object while it is attached to a control.
