Question

In iOS and Cocoa Touch, sometimes it seems we can get by without calling super, such as:

-(void) viewDidAppear:(BOOL)animated {
    // nothing weird if the following is not called:  
    //     [super viewDidAppear: animated]
    // but the docs says we should call it
}

and I think with drawRect, we usually won’t send super that same message, unless the super is doing some drawing of its own. Is it true that we should always send super the same message just to be safe in Cocoa Touch and iOS, and are there cases, then, not not send super the same message?

Answer 1

There’s no general rule, it always depends on the class you’re subclassing and method you’re overriding. NSObject is the root of the class hierarchy in (modern) Objective-C and obviously it doesn’t implement most of the methods you see and use, so always calling super wouldn’t make sense as a general rule.

You just have to check the documentation for each method separately.