Two finger swipe in UIScrollview for iPad applicat

问题:

Actually i want to implement swipe left and right in UIScrollview. i have scrollview with content size (768,1500). i have tried this but problem is that sometimes its not detecting swipe and perform scrolling there. so now i want to disable scrolling on 2 finger touch.

swipeGesture = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(nextswipedScreen:)] autorelease];
swipeGesture.numberOfTouchesRequired=2;
swipeGesture.direction = UISwipeGestureRecognizerDirectionLeft;         
[self addGestureRecognizer:swipeGesture];

swipeGesture = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(previousswipedScreen:)] autorelease];
swipeGesture.numberOfTouchesRequired=2;
swipeGesture.direction = UISwipeGestureRecognizerDirectionRight;            
[self addGestureRecognizer:swipeGesture]; 

i have tried custom scrollview for that but i have problem with touchesBegan method. its not calling every time. even i tried this but not able to stop two finger scroll in UIScrollview.

for (UIGestureRecognizer *mgestureRecognizer in _scrollView.gestureRecognizers) {     
        if ([mgestureRecognizer  isKindOfClass:[UIPanGestureRecognizer class]])
        {
            UIPanGestureRecognizer *mpanGR = (UIPanGestureRecognizer *) mgestureRecognizer;
            mpanGR.minimumNumberOfTouches = 1; 
            mpanGR.maximumNumberOfTouches = 1;
        }
    }

Let me know if you have any solution or alternative for that.

回答1:

I had the same problem; I needed to disable two-finger scrolling so that I could detect a two-finger swipe to the left or right. Here's what I did to set up my scroll view:

- (void) setUpGestureHandlersOnScrollView:(UIScrollView *)scrollView {
    // set up a two-finger pan recognizer as a dummy to steal two-finger scrolls from the scroll view
    // we initialize without a target or action because we don't want the two-finger pan to be handled
    UIPanGestureRecognizer *twoFingerPan = [[UIPanGestureRecognizer alloc] init];
    twoFingerPan.minimumNumberOfTouches = 2;
    twoFingerPan.maximumNumberOfTouches = 2;
    [scrollView addGestureRecognizer:twoFingerPan];

    // set up the two-finger left and right swipe recognizers
    UISwipeGestureRecognizer *twoFingerSwipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleGestureFrom:)];
    twoFingerSwipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
    twoFingerSwipeLeft.numberOfTouchesRequired = 2;
    [scrollView addGestureRecognizer:twoFingerSwipeLeft];

    UISwipeGestureRecognizer *twoFingerSwipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleGestureFrom:)];
    twoFingerSwipeRight.direction = UISwipeGestureRecognizerDirectionRight;
    twoFingerSwipeRight.numberOfTouchesRequired = 2;
    [scrollView addGestureRecognizer:twoFingerSwipeRight];

    // prevent the two-finger pan recognizer from stealing the two-finger swipe gestures
    // this is essential for the swipe recognizers to work
    [twoFingerPan requireGestureRecognizerToFail:twoFingerSwipeLeft];
    [twoFingerPan requireGestureRecognizerToFail:twoFingerSwipeRight];
}

The handler method should look something like this:

- (void)handleGestureFrom:(UISwipeGestureRecognizer *)recognizer {
    if ([recognizer numberOfTouches] == 2) {
        // do whatever you need to do
    }
}

回答2:

You can create two gesture recognizers, one for single tap and one for double tap:

UITapGestureRecognizer *singleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTouchesOne:)];
singleTapGesture.cancelsTouchesInView = NO; 
singleTapGesture.delaysTouchesEnded = NO;
singleTapGesture.numberOfTouchesRequired = 1; // One finger single tap
singleTapGesture.numberOfTapsRequired = 1;
[Scroll_view addGestureRecognizer:singleTapGesture];
[singleTapGesture release];

UITapGestureRecognizer *doubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTouchesTwo:)];
doubleTapGesture.cancelsTouchesInView = NO; 
doubleTapGesture.delaysTouchesEnded = NO;
doubleTapGesture.numberOfTouchesRequired = 1; // One finger double tap
doubleTapGesture.numberOfTapsRequired = 2;
[Scroll_view addGestureRecognizer:doubleTapGesture];
[doubleTapGesture release];

And then, here comes the punch:

[singleTapGesture requireGestureRecognizerToFail : doubleTapGesture];

requireGestureRecognizerToFail Reference

The last line, makes your single tap handler work only if the double tap fails. So, you get both single tap and double tap in your application.

And So you can do like, in "doubleTapGesture" method you just specified the scrollview with content size (0,0), In "singleTapGesture" method you specified the scrollview with content size (768,1500).

Source knowledge