myView.frame.origin.x = value; does not work - But why?

Question

I know that I can\'t use this:

myView.frame.origin.x = 25.0;

and that I have to use this instead:

CGRect myFrame = myView.f         


        

Answer 1

When you manipulate the data directly, no accessor is called, so the UI cannot update itself - or inform any other component that wants to know about changes.

Edit: As pointed out by walkytalky, you will get a copy of the data, so changing it doesn't have any effect on the original anyway. The following example will show this:

UIView *aView = [[UIView alloc] initWithFrame:CGRectMake(50,50,100,100)];
NSLog(@"%f", aView.frame.origin.x); // will give 50
aView.frame.origin.x = 17;  // operates on a copy of the rect only
NSLog(@"%f", aView.frame.origin.x);  // will still give 50