- (void)viewDidLoad
{
        //建立滑动手势
        UISwipeGestureRecognizer *recognizer;
        recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
        //设置滑动方向，下面以此类推
        [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
        [[self view] addGestureRecognizer:recognizer];
    
        recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
        [recognizer setDirection:(UISwipeGestureRecognizerDirectionUp)];
        [[self view] addGestureRecognizer:recognizer];
    
        recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
        [recognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];
        [[self view] addGestureRecognizer:recognizer];
    
        recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
        [recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
        [[self view] addGestureRecognizer:recognizer];
    
        [super viewDidLoad];
}

//这个是协议回调，所以需要遵循 UIGestureRecognizerDelegate协议
-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {
    NSLog(@"Swipe received.");
    if (recognizer.direction==UISwipeGestureRecognizerDirectionDown) {
        NSLog(@"向下滑动");
        //执行程序
    }
    if (recognizer.direction==UISwipeGestureRecognizerDirectionUp) {
        
        NSLog(@"向上滑动");
        //执行程序
    }
    if (recognizer.direction==UISwipeGestureRecognizerDirectionLeft) {
        
        NSLog(@"向左滑动");
        //执行程序
    }
    if (recognizer.direction==UISwipeGestureRecognizerDirectionRight) {
        
        NSLog(@"向右滑动");
        //执行程序
    }
}