Re: Custom Delegate - Using _delegate works but not delegate or [self delegate]
Re: Custom Delegate - Using _delegate works but not delegate or [self delegate]
- Subject: Re: Custom Delegate - Using _delegate works but not delegate or [self delegate]
- From: Conrad Shultz <email@hidden>
- Date: Mon, 25 Mar 2013 13:54:40 -0700
On Mar 25, 2013, at 12:47 PM, Chris Tracewell <email@hidden> wrote:
> I have a subclass of NSOutlineView that has custom delegate methods. In the implementation file I get an error for "No known instance method for selector..." when I call these declared methods using [self delegate] or delegate. However the compiler suggested using _delegate and that makes the error go away. I thought since my subclass inherits from NSOutlineView that delegate would be recognized and available.
"[self delegate]" is not the same as "delegate" - the former sends the -delegate message, the latter references a variable named "delegate" (which the compiler is telling you does not exist).
> -(void)keyDown:(NSEvent *)theEvent
> {
> if ([[theEvent characters] length] == 0)
> {
> // dead key
> return;
> }
> else if ([[theEvent characters] length] == 1 && [[theEvent characters] characterAtIndex:0] == NSEnterCharacter && [[self delegate] respondsToSelector:@selector(outlineView: enterKeyPressedForRow:)])
> {
> [delegate outlineView:self enterKeyPressedForRow:[self selectedRow]];
For example, here you correctly use "[self delegate]" in the if() condition but improperly fall back to merely "delegate" for actually dispatching your delegate message.
> Is _delegate the correct usage here or have I done something else wrong? Thank you.
The correct usage is [self delegate] in place of just "delegate." You could also create a local variable assigned to [self delegate] if you wish.
-Conrad
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