App crashes after adding gesture UITapGestureRecognizer to UILabel - ios

Question

I'm fairly new to Objective C. I am trying to add a tap gesture recognizer to the UILabel. But the app crashes when trying to call the selector method. Here's what I am doing.
- (instancetype)initWithCard:(Card *)obj {
//few lines of code here...
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self.selectionHeaderLabel action:#selector(onLabelTapped:)];
_selectionHeaderLabel.userInteractionEnabled = YES;
[self.selectionHeaderLabel addGestureRecognizer:tap];
}
-(void) onLabelTapped:(UITapGestureRecognizer *) recognizer {
if ([recognizer state] == UIGestureRecognizerStateEnded) {
//do some stuff
}
}
I followed this answer, but that is not helping me.
https://stackoverflow.com/a/9058735/4863339
EDIT: Here is the crash report
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UILabel onLabelTapped:]: unrecognized selector sent to instance 0x7f8c4f5252e0'
*** First throw call stack:
(
0 CoreFoundation 0x000000011027334b exceptionPreprocess + 171
1 libobjc.A.dylib 0x000000010f7d821e objc_exception_throw + 48
2 CoreFoundation 0x00000001102e2f34 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 CoreFoundation 0x00000001101f8c15 ___forwarding_ + 1013
4 CoreFoundation 0x00000001101f8798 _CF_forwarding_prep_0 + 120
5 UIKit 0x000000010da5f289 -[UIGestureRecognizerTarget _sendActionWithGestureRecognizer:] + 57
6 UIKit 0x000000010da67028 _UIGestureRecognizerSendTargetActions + 109
7 UIKit 0x000000010da64af7 _UIGestureRecognizerSendActions + 227
8 UIKit 0x000000010da63d83 -[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:] + 891
9 UIKit 0x000000010da4fe56 _UIGestureEnvironmentUpdate + 1395
10 UIKit 0x000000010da4f89b -[UIGestureEnvironment _deliverEvent:toGestureRecognizers:usingBlock:] + 521
11 UIKit 0x000000010da4ea7e -[UIGestureEnvironment _updateGesturesForEvent:window:] + 286
12 UIKit 0x000000010d58d7ad -[UIWindow sendEvent:] + 3989
13 UIKit 0x000000010d53aa33 -[UIApplication sendEvent:] + 371
14 UIKit 0x000000010dd2cb6d dispatchPreprocessedEventFromEventQueue + 3248
15 UIKit 0x000000010dd25817 __handleEventQueue + 4879
16 CoreFoundation 0x0000000110218311 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17
17 CoreFoundation 0x00000001101fd59c __CFRunLoopDoSources0 + 556
18 CoreFoundation 0x00000001101fca86 __CFRunLoopRun + 918
19 CoreFoundation 0x00000001101fc494 CFRunLoopRunSpecific + 420
20 GraphicsServices 0x0000000114460a6f GSEventRunModal + 161
21 UIKit 0x000000010d51cf34 UIApplicationMain + 159
22 CollPoll 0x000000010bdcf8df main + 111
23 libdyld.dylib 0x000000011267a68d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

I guess you are passing the target wrong. just pass self instead of self.selectionHeaderLabel.
Then, code will be like this :
- (instancetype)initWithCard:(Card *)obj {
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(onLabelTapped:)];
_selectionHeaderLabel.userInteractionEnabled = YES;
[self.selectionHeaderLabel addGestureRecognizer:tap];
}
Hope this works for you.