Objective C subclass that overrides a method in the superclass

objective-c overriding subclass
Andy White picture Andy White · Apr 21, 2009 · Viewed 14.3k times · Source

In Objective C, if you are subclassing something, and are planning to override a method on the superclass, should you re-declare the superclass method in your subclass @interface?

For example, if you are subclassing UIViewController (e.g. MyViewController), and you are planning to override "viewDidLoad" should you include that method in your MyViewController @interface declaration, or just implement it in MyViewController.m?

In examples I've come across, I've seen it done both ways (re-declaring the method in your subclass interface, or not re-declaring the method). There may not be any functional difference, but what is the best practice?

Answer

Jason Coco picture Jason Coco · Apr 21, 2009

I often declare methods that I plan to override in either the public header or at least in a private category. The benefit to this is that you'll get an incomplete class definition warning if you forget to actually override the method... which comes in handy from time to time.

As for when to place it in the public header, that's pretty subjective and probably up to you/your team's coding styles. I usually only redeclare a method in the public header if I plan to radically change what the method is going to do or if I plan not to invoke the super class's version of the method.

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