iPhone模拟器向右滑动有效，但向左滑动不起作用？

Question

I'm trying to use swipe left and right on a UIScrollView. However it looks like swipe left does not work in iPhone simulator even though swipe right does. Did I miss any step?

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

    self.scrollView.multipleTouchEnabled = YES;
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
    swipe.delaysTouchesBegan = YES;
    swipe.numberOfTouchesRequired = 2;
    [self.scrollView addGestureRecognizer:swipe];
    [swipe release];
}

- (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer
{
    if (recognizer.direction == UISwipeGestureRecognizerDirectionLeft) {

    } else if (recognizer.direction == UISwipeGestureRecognizerDirectionRight) {

    }
}

Answer 1

Use Following:

UISwipeGestureRecognizer *rightRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(rightSwipeHandle:)];
rightRecognizer.direction = UISwipeGestureRecognizerDirectionRight;
[rightRecognizer setNumberOfTouchesRequired:1];
[mainSlideShowImageScrollView addGestureRecognizer:rightRecognizer];
[rightRecognizer release];
UISwipeGestureRecognizer *leftRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(leftSwipeHandle:)];
leftRecognizer.direction = UISwipeGestureRecognizerDirectionLeft;
[leftRecognizer setNumberOfTouchesRequired:1];
[mainSlideShowImageScrollView addGestureRecognizer:leftRecognizer];
[leftRecognizer release];   



- (void)rightSwipeHandle:(UISwipeGestureRecognizer*)gestureRecognizer 
   {
      //Do moving
   }

- (void)leftSwipeHandle:(UISwipeGestureRecognizer*)gestureRecognizer 
{
  // do moving
}

Answer 2

Your 'handleSwipe' code is actually correct. You need two UISwipeGestureRecognizers but you can point them both to the same handler, containing your 'IF' statement.

Answer 3

You can create one gesture recognizer that handles both left and right swipe (or even all directions-:):

    UISwipeGestureRecognizer *swipeGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
        swipeGesture.direction = UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight;

All directions:

  swipeGesture.direction = UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight | UISwipeGestureRecognizerDirectionUp | UISwipeGestureRecognizerDirectionDown;