What is the correct usage of the UIView beginAnimations and context parameters
Almost every example I've seen for the beginAnimations:Context: method has been used nil (or NULL) for its parameters like this:

`[UIView beginAnimations:nil context:nil];`

But I found out that if I want to utilize other capabilities such as removeAnimationForKey then I must have a value for the context parameter.
But I can't figure out what object type the context parameter is supposed to be because the class definition says it's a pointer to void: 
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIView_Class/UIView/UIView.html

Anybody familiar with how these parameters work in better detail?
What is the correct usage of the UIView beginAnimations and context parameters
===

Almost every example I've seen for the beginAnimations:Context: method has been used nil (or NULL) for its parameters like this:

`[UIView beginAnimations:nil context:nil];`

But I found out that if I want to utilize other capabilities such as removeAnimationForKey then I must have a value for the context parameter.
But I can't figure out what object type the context parameter is supposed to be because the class definition says it's a pointer to void: 
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIView_Class/UIView/UIView.html

Anybody familiar with how these parameters work in better detail?