UIPanGestureRecognizer判断滑动的方向

.h文件

CGFloat const gestureMinimumTranslation = 20.0 ;
typedef enum : NSInteger {
    kCameraMoveDirectionNone,
    kCameraMoveDirectionUp,
    kCameraMoveDirectionDown,
    kCameraMoveDirectionRight,
    kCameraMoveDirectionLeft
} CameraMoveDirection ;

@interface FCDetailViewController : FCMainViewController
{
    CameraMoveDirection direction;
}

.m文件  --------

- (void)viewDidLoad
{
    [super viewDidLoad];

    //监听滑动手势
    UIPanGestureRecognizer *recognizer = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handleSwipeFrom:)];
    [self.view addGestureRecognizer:recognizer];
}

- (void)handleSwipeFrom:(UIPanGestureRecognizer*)gesture
{
    CGPoint translation = [gesture translationInView:self.view];
    if (gesture.state == UIGestureRecognizerStateBegan ){
        direction = kCameraMoveDirectionNone;

    }else if(gesture.state == UIGestureRecognizerStateChanged && direction == kCameraMoveDirectionNone){
        direction = [ self determineCameraDirectionIfNeeded:translation];

        switch (direction) {
            case kCameraMoveDirectionDown:
                //NSLog (@ "Start moving down" );
                break ;

            case kCameraMoveDirectionUp:
                //NSLog (@ "Start moving up" );
                break ;

            case kCameraMoveDirectionRight:
                //NSLog (@ "Start moving right" );
                break ;

            case kCameraMoveDirectionLeft:
                //NSLog (@ "Start moving left" );
                break ;

            default :
                break ;
        }

    }else if(gesture.state == UIGestureRecognizerStateEnded){
        //NSLog (@ "Stop" );
    }
}

- (CameraMoveDirection)determineCameraDirectionIfNeeded:(CGPoint)translation
{
    if (direction != kCameraMoveDirectionNone)
        return direction;

    if (fabs(translation.x) > gestureMinimumTranslation){
        BOOL gestureHorizontal = NO;
        if (translation.y == 0.0)
            gestureHorizontal = YES;
        else
            gestureHorizontal = (fabs(translation.x / translation.y) > 5.0);

        if(gestureHorizontal){
            if (translation.x > 0.0)
                return kCameraMoveDirectionRight;
            else
                return kCameraMoveDirectionLeft;
        }

    }else if(fabs(translation.y) > gestureMinimumTranslation){
        BOOL gestureVertical = NO;

        if (translation.x == 0.0)
            gestureVertical = YES;
        else
            gestureVertical = (fabs(translation.y / translation.x) > 5.0);

        if(gestureVertical){
            if (translation.y > 0.0)
                return kCameraMoveDirectionDown;
            else
                return kCameraMoveDirectionUp;
        }
    }
    return direction;
}