Do I programmatically add SubViews in ViewDidAppear, ViewDidLoad, ViewWillAppear, the constructor?

Question

I\'m trying to figure out from Apple\'s sketchy documentation which method is the best place to be initializing and adding my Views controls to the controller\'s view.

Answer 1

viewDidLoad relates to 'MEMORY', and viewWillAppear/viewDidAppear relates to 'APPEARANCE'. A view controller's view (which is a root-view of your view controller's views) can appear/disappear numerous times, even if the controller's view is already in memory.

(When referring to root-view, I also means its subviews, because the root-view has reference to its children (subviews), but from a view controller's perspective, it usually knows just the root-view. Reference to subviews can happens normally through view controller's outlets.)

The root-view itself MAY be removed from memory when there's a memory warning. The view controller will determine when is the best time to removed them from memory.

So, you would normally add subviews in viewDidLoad, because adding subviews means adding them to memory. BUT not if you create all of your views programmatically (not from a nib files). If that's the case then you should override loadView method, and create a root-view and add subviews there, so in this case you can omit viewDidLoad to add subviews.