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Can we rely on the fact that in Objective-C, the rule is that a class's designated initializer is always called for sure? Or can we say, it should be almost always true, except a couple of exceptions? For example, for UIView, the docs says:

initWithFrame:

If you create a view object programmatically, this method is the designated initializer for the UIView class. Subclasses can override this method to perform any custom initialization but must call super at the beginning of their implementation.

If you use Interface Builder to design your interface, this method is not called when your view objects are subsequently loaded from the nib file. Objects in a nib file are reconstituted and then initialized using their initWithCoder: method

Or can we say that, if it is programmatically, the rule should always apply for well designed classes, but Interface Builder is a bit different because it sort of "revive" or build the object from a non-programmatic way. If so, are they other exceptions in general when we do iOS programming?

Community
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Jeremy L
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1 Answers1

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The fact is that class designed with Interface Builder are unarchived and not initialized .

Being archived involves that the class is not initialized but unarchived, so the initWithCoder: method takes responsibility for setting up the control when it's loaded using the archived attributes configured by Interface Builder.

You should put your initialization operations in the awakeFromNib: method that gets called in each case after the object is loaded, thus you will be sure that your initialization statements will be called .

aleroot
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  • `awakeFromNib:` doesn’t get called when you create the object programmatically. I’d recommend doing the initial setup in `layoutSubviews` (for `UIView` subclasses) – Sven Sep 22 '12 at 09:05