UIGestureRecognizer not working - ios

Question

Not sure what i'm doing wrong but here's a simplified example:
#interface Test : NSObject<UIGestureRecognizerDelegate> {
UIView *_someParentView;
UIView *_someChildView;
}
- (id)initWithParentView:(UIView *)parentView;
#end
#implementation Test
- (id)initWithParentView:(UIView *)parentView
{
if (self = [super init])
{
_someParentView = parentView;
}
return self;
}
- (void)addSubViewsWhenReady
{
_someChildView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
_someChildView.backgroundColor = [UIColor blackColor];
[_someChildView setUserInteractionEnabled:YES];
[_someParentView addSubview:_someChildView];
UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleSingleTap:)];
singleFingerTap.delegate = self;
[_someChildView addGestureRecognizer:singleFingerTap];
}
- (void)handleSingleTap:(id)sender
{
NSLog(#"handle the single tap");
}
#end
The output: "handle the single tap" is never logged. Any ideas on what im doing wrong?
Thanks!

Answer 1

Setting the target like you are doing:
UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleSingleTap:)];
is your problem. If "self" here is a UIViewController, it will work.
i.e.
#interface Test : UIViewController<UIGestureRecognizerDelegate> {
UIView *_someParentView;
UIView *_someChildView;
}
- (id)initWithParentView:(UIView *)parentView;
#end
#implementation Test
- (id)initWithParentView:(UIView *)parentView
{
if (self = [super init])
{
_someParentView = parentView;
}
return self;
}
- (void)addSubViewsWhenReady
{
_someChildView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
_someChildView.backgroundColor = [UIColor blackColor];
[_someChildView setUserInteractionEnabled:YES];
[_someParentView addSubview:_someChildView];
UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleSingleTap:)];
singleFingerTap.delegate = self;
[_someChildView addGestureRecognizer:singleFingerTap];
}
- (void)handleSingleTap:(UIGestureRecognizer*)recognizer {
NSLog(#"handle the single tap");
}
#end

Answer 2

Try changing your definition of handleSingleTap: to
- (void)handleSingleTap:(UIGestureRecognizer*)recognizer {
NSLog(#"handle the single tap");
}
From the UIGestureRecognizer docs:
A gesture recognizer has one or more target-action pairs associated with it. If there are multiple target-action pairs, they are discrete, and not cumulative. Recognition of a gesture results in the dispatch of an action message to a target for each of those pairs. The action methods invoked must conform to one of the following signatures:
- (void)handleGesture;
- (void)handleGesture:(UIGestureRecognizer *)gestureRecognizer;