How does [UIView beginAnimations] work?

Question

I was wondering how animations work in Cocoa Touch. For example:

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:1.0];

view1.alpha = 1.0         


        

Answer 1

A simplified explanation:

All animations for all views are handled on a single stack, beginAnimations:context: will push a new active CAAnimationGroup on the stack, and commitAnimations will pop the current active animation group.

If there is an active animation group on the stack, then all setters for animatable properties will create CAAnimation subclass instances to handle that property and add then to the active animation group.

When the last animation is popped, it is replayed.