What's an IBAction?

[rharder]

A method that's called as an action from Interface Builder has the signature
- (IBAction)actionName: (id)sender.

What's an IBAction? Is it an object (an id)? A constant?

I don't return anything from these methods, but could I?

-Rob

 

[endian]

I don't return anything from these methods, but could I?

Nope, IBAction is defined as void. It's just there so IB can parse your header when you drag it into IB.

 

[rharder]

If I have an IBAction method, will its return value be nil if I do something like this:

id obj = [self buttonPressed:self];

-Rob

 

[endian]

i doubt that'd even compile.. it'll probably say something like 'assigning void value should be ignored.' void isn't nil, it's just nothing.

not sure what you're trying to do, but you can differentiate between multiple buttons calling the same action with the tag instance variable - give each button a unique tag value, then do something like

-(IBAction)buttonPressed:(id)sender
{
	switch ( [sender tag] )
	{
	case 1:
	//blah blah blah
	break;

	case 2:
	//blah blah etc.
	break;
	}
}

You could obviously call your own methods and return whatever you want from there.

 

[rharder]

I was wondering if I could use an IBAction method by invoking a selector at run-time which is a trick I'm trying with the ThreadWorker class (http://iharder.net/macosx/threadworker).

I'm away from any NS*-capable compiler for a while, so I can't experiment.

-Rob

 

[endian]

you can invoke it at runtime, you just can't return anything.

e.g. [window makeKeyAndOrderFront:nil];

 

[rharder]

So I finally got back to my OS X box, and yes, you can set a variable equal to the return value of a method that returns void (or at least, IBAction). Essentially, you're setting the variable to nil. That's not a problem.

-Rob