app crashing when responding to tapgesture - ios

Question

Basically, I have a UIViewController with a xib built for holding content in a UIScrollView. this gets populated from an RSS feed. this works as expected. I want a tap on the UIView that the view controller owns to respond to a tap and continue on its way. however, a tap crashes the app with the "unrecognized selector sent to instance" error. I really have no clue what's going on.
The .h file of the xib's view controller looks like this:
#property (nonatomic,retain) IBOutlet UIImageView *article_image;
#property (nonatomic,retain) IBOutlet UILabel *article_title;
#property (nonatomic,retain) IBOutlet UILabel *article_date;
#property (nonatomic,retain) IBOutlet UIActivityIndicatorView *spinner;
#property (nonatomic,retain) NSString *preview_image;
- (void) loadPreviewImage;
Then the .m file looks like this:
- (void)viewDidLoad {
[super viewDidLoad];
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGesture)];
singleTap.numberOfTapsRequired = 1;
[self.view addGestureRecognizer:singleTap];
self.view.layer.shadowColor = [UIColor blackColor].CGColor;
self.view.layer.shadowOpacity = 0.6;
self.view.layer.shadowRadius = 1.5;
self.view.layer.shadowOffset = CGSizeMake(0, 0);
}
- (void) singleTapGesture:(UITapGestureRecognizer *)gesture {
NSLog(#"TAPPED!");
}
Even if I put just a simple roundrectbutton in the xib and attach it to an IBAction - it crashes, so I'm figuring there's something wrong with how my xib is set up, but I have no clue as to what. those properties in the .h get populated just fine from the VC that holds the scrollview, so the xib obviously knows the file it's associated with, so I just can't figure out why it's crashing and throwing that error on a tap.

Answer 1

The fix is this:
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGesture:)];
notice the : at the end of the selector.
Indeed, your action method signature is:
- (void) singleTapGesture:(UITapGestureRecognizer *)gesture;
while
#selector(singleTapGesture)
would rather identify:
- (void) singleTapGesture;
Hope this clarifies the issue.

Answer 2

well, i never really figured out exactly what was causing the crash - so i wound adding the gesture recognizer to the objects into the loop that builds them and all works great. not how i'd like to have done it (was trying to keep it in the object's class definition) but whatever. perhaps this will help someone else.