CODEWITHSUNDEEP
objective-ciosoopclass
Rebecca Allision
Rebecca Allision

Reputation: 11

calling super class question

I'm wondering what happens in this case of class hierarchy

MySuperClass : UIViewController

MYSubClass : MySuperClass

MySuperClass lack the method, ViewWillAppear

My question is: if MySubClass has the following method

- (void)viewWillAppear:(BOOL)animated 
{
    [super viewWillAppear:animated];
}

is that code simply ignored (won't be executed) or viewWillAppear in UIViewController will be called?

Just wondering.

Upvotes: 1

Views: 620

Answers (2)

Caleb
Caleb

Reputation: 125037

Say you have:

MySubClass *mySubController = [[MySubClass alloc] initWithNibNamed:nil bundle:nil];

If you do something with mySubController that will cause its view to appear, like push it onto a nav controller's stack, then MySubClass' implementation of -viewWillAppear will be called. As it is now, that implementation just calls super's implementation. Since MySuperClass doesn't override -viewWillAppear, UIViewController's implementation will be called.

Upvotes: 0

ughoavgfhw
ughoavgfhw

Reputation: 39925

It works similarly to normal method calls. When you call on super, the runtime goes up through the chain of superclasses until it finds one that implements the requested method. If it doesn't find one, it will call forwarding methods, and if the method isn't forwarded it will call doesNotRecognizeSelector:. So, yes, viewWillAppear will be called on the UIViewController class.

Upvotes: 3

Related Questions