Intro to Animations
The easiest way to add animations to your application is using the UIView animation class methods. For instance, the following code demonstrates how to fade out a view:
The default alpha value for a view starts at 1, which means the view is not transparent at all. Over the course of two seconds, the view will fade out until it is completely invisible.
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Note that all the UIView methods above are called directly on the UIView class itself—not on a UIView instance. That’s because beginAnimations:contentxt:, setAnimationDuration:, ...