Can UIView be copied?

Simply using this way:

UIView* view2 = [view1 copy]; // view1 existed

This will cause simulator can not launch this app.

Try retain,

UIView* view2 = [view1 retain]; // view1 existed
// modify view2 frame etc

Any modifications to view2 will apply to view1, I understand that view2 share same memory with view1.

Why can't UIView be copied? What is the reason?

this might work for you ... archive the view and then unarchive it right after. This should give you a deep copy of a view:

id copyOfView = 
[NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:originalView]];

Your app probably crashes with something like:

 [UIView copyWithZone:]: unrecognized selector sent to instance 0x1c6280

The reason is that UIView does not implement the copying protocol, and therefore there is no copyWithZone selector in UIView.