Why it doesn't recognise my selector?

I want to change the action of an UIButton and it gives me an exception when touching the button.

[grabRedeem removeTarget:self ac开发者_C百科tion:@selector(grabbOffer:) forControlEvents:UIControlEventTouchUpInside];
[grabRedeem addTarget:self action:@selector(redeemOffer:) forControlEvents:UIControlEventTouchUpInside];

grabbOffer and redeemOffer are IBActions that are implemented with no parameters.

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[DetailViewController grabbOffer:]: unrecognized selector sent to instance 0x1e8bf0'

What could be the reason?

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Have you tried to remove the colon:

[grabRedeem removeTarget:self action:@selector(grabbOffer) forControlEvents:UIControlEventTouchUpInside];
[grabRedeem addTarget:self action:@selector(redeemOffer) forControlEvents:UIControlEventTouchUpInside];

you use the semicolon when you want to use a parameter:

-(void)grabbOffer:(id)sender;

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If you function implemented with no parameters use: @selector(grabbOffer) instead @selector(grabbOffer:)