iphone开发中的手势操作：Swipes

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    gestureStartPoint = [touch locationInView:self.view];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint currentPosition = [touch locationInView:self.view];
    
    CGFloat deltaX = fabsf(gestureStartPoint.x - currentPosition.x);
    CGFloat deltaY = fabsf(gestureStartPoint.y - currentPosition.y);
    
    if (deltaX >= kMinimumGestureLength && deltaY <= kMaximumVariance) {
        label.text = @"Horizontal swipe detected";
        [self performSelector:@selector(eraseText)
                   withObject:nil afterDelay:2];
    } else if (deltaY >= kMinimumGestureLength &&
               deltaX <= kMaximumVariance){
        label.text = @"Vertical swipe detected";
        [self performSelector:@selector(eraseText) withObject:nil
                   afterDelay:2];
    }
}

亦可以使用Automatic Gesture Recognition ：(UIGestureRecognizer)

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    UISwipeGestureRecognizer *vertical = [[UISwipeGestureRecognizer alloc] 
            initWithTarget:self action:@selector(reportVerticalSwipe:)];
    vertical.direction = UISwipeGestureRecognizerDirectionUp| 
    UISwipeGestureRecognizerDirectionDown;
    [self.view addGestureRecognizer:vertical];
    
    UISwipeGestureRecognizer *horizontal = [[UISwipeGestureRecognizer alloc] 
            initWithTarget:self action:@selector(reportHorizontalSwipe:)];
    horizontal.direction = UISwipeGestureRecognizerDirectionLeft| 
    UISwipeGestureRecognizerDirectionRight;
    [self.view addGestureRecognizer:horizontal];
}

然后加上自定义的两个响应方法：

- (void)reportHorizontalSwipe:(UIGestureRecognizer *)recognizer {
    label.text = @"Horizontal swipe detected";
    [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
}

- (void)reportVerticalSwipe:(UIGestureRecognizer *)recognizer {
    label.text = @"Vertical swipe detected";
    [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
}

就OK啦！

以上的只是单个轻扫动作，下面的是多个轻扫动作同时进行的情况：

在viewDidLoad中添加循环：

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    for (NSUInteger touchCount = 1; touchCount <= 5; touchCount++) {
        UISwipeGestureRecognizer *vertical;
        vertical = [[UISwipeGestureRecognizer alloc] initWithTarget:self
                                                             action:@selector(reportVerticalSwipe:)];
        vertical.direction = UISwipeGestureRecognizerDirectionUp| 
        UISwipeGestureRecognizerDirectionDown;
        vertical.numberOfTouchesRequired = touchCount;
        [self.view addGestureRecognizer:vertical];
        
        UISwipeGestureRecognizer *horizontal;
        horizontal = [[UISwipeGestureRecognizer alloc] initWithTarget:self
                                                               action:@selector(reportHorizontalSwipe:)];
        horizontal.direction = UISwipeGestureRecognizerDirectionLeft| 
        UISwipeGestureRecognizerDirectionRight;
        horizontal.numberOfTouchesRequired = touchCount;
        [self.view addGestureRecognizer:horizontal];
    }
}

修改对于响应动作函数：

- (void)reportHorizontalSwipe:(UIGestureRecognizer *)recognizer {
    label.text = [NSString stringWithFormat:@"%@Horizontal swipe detected",
                  [self descriptionForTouchCount:[recognizer numberOfTouches]]];
    [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
}

- (void)reportVerticalSwipe:(UIGestureRecognizer *)recognizer {
    label.text = [NSString stringWithFormat:@"%@Vertical swipe detected",
                  [self descriptionForTouchCount:[recognizer numberOfTouches]]];;
    [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
}

- (NSString *)descriptionForTouchCount:(NSUInteger)touchCount {
    switch (touchCount) {
        case 2:
            return @"Double ";
        case 3:
            return @"Triple ";
        case 4:
            return @"Quadruple ";
        case 5:
            return @"Quintuple ";
        default:
            return @"";
    }
}