progressHandler
A custom block that runs at the same time as the system animations.
Declaration
var progressHandler: ((Float) -> Void)? { get set }Discussion
If you have animations you want to run at the same time as the system animations, assign a block to this property and use it to run your animations. The block you provide must have no return value and take a floating-point value as a parameter. The parameter indicates the current progress of the animations as a percentage value between 0.0 to 1.0. The system executes your block multiple times during the course of the animations, providing an updated completion value each time.