Question

This bug is befuddling to me, but here goes:

I was trying to set up an IBAction to run on touch up inside on a UIButton. For some reason, it wasn’t working, and wasn’t really giving me any gdb errors. Every now and then it would mention an unrecognized selector. I checked to make sure my File’s owner was the correct class, and everything was in check and it was, so I ran it again and still nothing.

I figured it might be a problem with Interface Builder, so I used addTarget: on the button, setting the target as self, and the selector the selector of the method I wanted to call, and still got an unrecognized selector error. To test that the selector did exist, I ran a [self performSelector:] on the selector of the method I wanted, and it worked. So basically right now I have this:

- (void)viewDidLoad {
    [super viewDidLoad];

    [self performSelector:@selector(hi)];

    [_backButton addTarget:self action:@selector(hi) forControlEvents:UIControlEventTouchUpInside];
}

- (void)hi {
    NSLog(@"HI");
}

The perform selector works perfectly, and logs “HI”. Here’s the kicker, when I touchup on _backButton, it gives me an unrecognized selector error, even though I just called it and it worked:

2011-10-22 19:54:40.824 VideoGif[396:707] -[NSKeyValueObservance hi]: unrecognized selector sent to instance 0x590690
2011-10-22 19:54:40.831 VideoGif[396:707] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSKeyValueObservance hi]: unrecognized selector sent to instance 0x590690'

I’ve taken screen shots of the nib and the implementation file, viewable here: https://i.stack.imgur.com/D9GsW.jpg

Does anyone know what’s going on?

Answer 1

The problem is probably happening because your instance of CaptionEditorViewController is being deallocated for some reason, as pointed by random classes throwing “unrecognized selector” exceptions