cannot update view.layer.frame in viewDidLoad?

Question

I am trying to execute following code in viewDidLoad method of my single view controller project:

self.view.layer.frame = CGRectInset(self.view.layer.frame, 20,          


        

Answer 1

Rob Mayoff's answer is correct and excellent, but putting it a slightly different way: viewDidLoad only means the view has loaded, i.e. that the view controller has obtained its view. It doesn't mean that the view has been placed in the interface. That, indeed, is one of the things that viewDidAppear: does mean — and that's why it worked when you ran your code there.

The trick in this sort of situation, where you want to initialize something about the view, is to do it late enough but do it only once. viewDidAppear: could easily be called again later, but you don't want to initialize the view again (unless it has been unloaded). In iOS 5, isMovingToParentViewController allows you to distinguish the particular circumstances you're looking for. Before that, it might be necessary to set up a BOOL flag so that you perform final initializations only once.

A related trap is what happens when the app launches into landscape orientation. Here, too, viewDidLoad is too soon because the interface has not yet rotated into landscape.

However, this issue should not be arising at all. It should be none of your business to inset a view controller's view. Either the view is the root view controller, in which case its size is correctly taken care of automatically, or it is the child of a parent view controller, in which case it is the parent view controller's job to size the view (as UINavigationController, for example, already does), or the view is to be presented modally, in which case its size will be set automatically to match the view it replaces. So I would suggest that you very question suggests you're doing something wrong.