iOS7: UITapGestureRecognizer reuse issue

Question

I set three buttons. Every button is tagged 1...3.

My UITapGestureRecognizer works only once and only for first UIButton. Can't select other two options. Code:

- (void)viewDidLoad
{
    [super viewDidLoad];

    UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(buttonTapped:)];
    recognizer.delegate = self;
    recognizer.cancelsTouchesInView = NO;
    [recognizer setNumberOfTapsRequired:1];
    [_btnNegative addGestureRecognizer:recognizer];
    [_btnNeutral addGestureRecognizer:recognizer];
    [_btnPositive addGestureRecognizer:recognizer];
}

And the buttonTapped: method:

-(void)buttonTapped:(UITapGestureRecognizer *)recognizer
{
    switch (((UIGestureRecognizer *)recognizer).view.tag)
    {
         case 1:
        {
            NSLog(@"Positive");
            [_btnPositive setBackgroundImage:[UIImage imageNamed:@"checkedBox"] forState:UIControlStateNormal];
            [_btnNegative setBackgroundImage:[UIImage imageNamed:@"UncheckedBox"] forState:UIControlStateNormal];
            [_btnNeutral setBackgroundImage:[UIImage imageNamed:@"UncheckedBox"] forState:UIControlStateNormal];
            _opinion=@"Positive";
            break;
        }
        case 2:
        {
            NSLog(@"Negative");
            [_btnNegative setBackgroundImage:[UIImage imageNamed:@"checkedBox"] forState:UIControlStateNormal];
            [_btnPositive setBackgroundImage:[UIImage imageNamed:@"UncheckedBox"] forState:UIControlStateNormal];
            [_btnNeutral setBackgroundImage:[UIImage imageNamed:@"UncheckedBox"] forState:UIControlStateNormal];
            _opinion=@"Negative";
            break;
        }
        case 3:
        {
            NSLog(@"Neutral");
            [_btnNeutral setBackgroundImage:[UIImage imageNamed:@"checkedBox"] forState:UIControlStateNormal];
            [_btnNegative setBackgroundImage:[UIImage imageNamed:@"UncheckedBox"] forState:UIControlStateNormal];
            [_btnPositive setBackgroundImage:[UIImage imageNamed:@"UncheckedBox"] forState:UIControlStateNormal];
            _opinion=@"Neutral";
            break;
        }
    }
}

Only case:1 works. Other cases never get called. I rechecked the button tags and are ok 1...3. Your help is much appreciated.

Answer 1

No, you can't reuse the same gesture recognizer. A gesture recognizer is designed to be attached to one and only one view.

Answer 2

I had the same problem Try to assign a new UITapGestureRecognizer to each button:

 UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self      action:@selector(buttonTapped:)];
recognizer.delegate = self;
recognizer.cancelsTouchesInView = NO;
[recognizer setNumberOfTapsRequired:1];
[_btnNegative addGestureRecognizer:recognizer];

 recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self      action:@selector(buttonTapped:)];
[_btnNeutral addGestureRecognizer:recognizer];

 recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self      action:@selector(buttonTapped:)];
[_btnPositive addGestureRecognizer:recognizer];