Question

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?

Answer 1

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.