Question

I set up my user interface in an xib file and got everything working pretty well. But the xib file was pretty cluttered, so I decided to try to create some of the buttons/bars/etc. programmatically instead. I can get them to show up fine, but I’m doing something wrong with the selectors.

With an instructions button on the xib file, for instance, I just used the mouse to connect the instructions button with the giveInstructions method in the .h file, and everything was fine. But when I try it programmatically, like so:

UIBarButtonItem *instr = [[UIBarButtonItem alloc] initWithTitle:@"Instructions" 
                                                          style:UIBarButtonSystemItemDone target:nil action:@selector(giveInstructions:)];

I get an unrecognized selector sent to instance error. What am I doing wrong?

Answer 1

Seeing as you fixed the target problem, it is most likely that “giveInstructions” doesn’t exist, at least not in this class’s implementation.

If you have declared

- (void)giveInstructions:(id)sender;

In your .h, it is imperative that you have a matching implementation in your .m file, e.g.:

- (void)giveInstructions:(id)sender{
    //my code here
}

If you have done this already, then the only other thing I can think of that could be wrong is that in your @selector(giveInstructions:) the colon may be unnecessary if you don’t have a sender, or any other arguments passed from the method.

Note: When calling @selector if the method you are calling is 1 character different from its actual declared name you will get this error because the selector doesn’t exist.