Question

I was wondering: what’s the difference between writing a selector name with no colon @selector(mySelector), or @selector(mySelector:) with the colon?

As in:

UIBarButtonItem *addButton = [[UIBarButtonItem alloc]initWith... 
                                                       target:self
                                                       action:@selector(addAction:)];

I can’t find another example without the colon, but I’m quite sure I have already seen some of them.

Answer 1

The colon is needed after the method’s name if and only if the method takes an argument.

No function parameters:

-(void)addAction {}

// Use ...@selector(addAction)...

Has parameter:

-(void)addAction:(id)info {}

// Use ...@selector(addAction:)...