Question

i have created a label and set tap gesture on it but it show me error when i tap on it.

my code is .h file

@interface ViewController : UIViewController
{
    UILabel *alabel;
}
@property (strong, nonatomic) UILabel *alabel;

in .m file

- (void)viewDidLoad
{
    [super viewDidLoad];

    alabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 10, 100, 50)];
    alabel.text = @"Drag me!";

    alabel.userInteractionEnabled = YES;

    UITapGestureRecognizer *tapGesture =[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(labelTap)];
    [alabel addGestureRecognizer:tapGesture];

    [self.view addSubview:alabel];
}

- (void)labelTap:(UITapGestureRecognizer *)tapGesture {
    TouchLabelViewController *touchLabelViewController = [[TouchLabelViewController alloc] initWithNibName:@"TouchLabelViewController" bundle:[NSBundle mainBundle]];
    [self presentModalViewController:touchLabelViewController animated:NO];
    }

log display

2012-10-29 11:19:17.313 DragableControll[795:f803] -[ViewController labelTap]: unrecognized selector sent to instance 0x68956b0
2012-10-29 11:19:17.316 DragableControll[795:f803] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ViewController labelTap]: unrecognized selector sent to instance 0x68956b0'

Answer 1

See your code you were wrongly adding the Selector to the Tap gesture

  UITapGestureRecognizer *tapGesture =[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(labelTap)];

you should do as

   UITapGestureRecognizer *tapGesture =[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(labelTap:)];