Question

I have a UIController and as you all know UIController is associated to a view and you can access it using the getter and setters methods which are synthesized

UIController controller = init code ..

..
controller.view -> this gives me my UIView object which retained and autoreleased, this will be synthesized get method(If at all my synthesized getmethod understanding is correct)

controller.view.frame -> this gives me my CGRect struct

controller.view.frame.size -> CGSize struct

why cannot I assign a value directly to this frame structure

controller.view.frame.size.width = 20;

for the above statement I get this error “lvalue required as left operand of assignment”

This is a normal c dot operator I think it should work.Please enlighten if I am missing anything

Answer 1

Using the dot operator in this situation is using the frame getter method behind the scenes. Since the frame property is a CGRect, which is a simple C struct, frame returns you a copy of the value, not a pointer to the value. Changing it will modify the CGRect you have copied locally on the stack, not the CGRect of your view’s frame property. To update the actual frame property you must go through the setter method [yourView setFrame:yourNewFrame]; or yourView.frame = yourNewFrame;.