在UIScrollView中为标准Pan Gesture Recognizer添加功能

Question

I am trying to keep track of where a finger is in a UIScrollView . I have subclassed UIScrollView (see below) but unfortunately the gesture recognizer that I am adding is overriding the standard one.

As a result I get NSLog(@"Pan") to work but unfortunately the view doesn't scroll anymore.

How can I get both gestures recognizers to work at the same time?

Thanks.

- (void)viewDidLoad:(BOOL)animated
{
    [super viewDidLoad:animated];

    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    [scrollView addGestureRecognizer:panRecognizer];
}


- (void)pan:(id)sender {
    NSLog(@"Pan");
}

Answer 1

If you want it not to override the standard one you just have to allow both to be simultaneously recognized.

- (void)viewDidLoad:(BOOL)animated
{
    [super viewDidLoad:animated];

    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    panRecognizer.delegate = self;
    [scrollView addGestureRecognizer:panRecognizer];
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
     return TRUE;
}


- (void)pan:(id)sender {
    NSLog(@"Pan");
}

Answer 2

EDIT : this method works! You just need to set canCancelContentTouches as soon as possible (I do it in viewDidLoad ).

ORIGINAL ANSWER : I have tried a new approach but unfortunately it doesn't fully work.

Instead of adding a gesture recognizer I am subclassing the UIScrollView and writing my own touchesBegan , touchesMoved , etc methods.

This way I know where the user is touching BUT unfortunately the PanGestureRecognizer is triggering touchesCancelled every time I start to scroll even after setting the canCancelContentTouches to NO .

Does anybody know why? I have also found this .