CXSwipeGestureRecognizer

UIGestureRecognizer subclass that takes much of the effort out of managing directional swipes.

CXSwipeGestureRecognizer *gestureRecognizer = [[CXSwipeGestureRecognizer alloc] init];
gestureRecognizer.delegate = self;
[self.view addGestureRecognizer:gestureRecognizer];

✓ Keeps track of both the current direction and the direction the gesture was started in.

if (gestureRecognizer.initialDirection == CXSwipeGestureDirectionUpwards) {
    if (gestureRecognizer.currentDirection == CXSwipeGestureDirectionDownwards) {
        NSLog(@"Gesture recognizer started swiping upwards and then changed direction");
    }
}

✓ Delegate protocol methods for start, update, cancel, and finish.

- (void)swipeGestureRecognizerDidStart:(CXSwipeGestureRecognizer *)gestureRecognizer
{
    NSLog("Gesture recognizer started");
}

- (void)swipeGestureRecognizerDidUpdate:(CXSwipeGestureRecognizer *)gestureRecognizer
{
    NSLog("Gesture recognizer updated");
}

- (void)swipeGestureRecognizerDidCancel:(CXSwipeGestureRecognizer *)gestureRecognizer
{
    NSLog("Gesture recognizer cancelled");
}

- (void)swipeGestureRecognizerDidFinish:(CXSwipeGestureRecognizer *)gestureRecognizer
{
    NSLog("Gesture recognizer finished");
}

✓ Convenience methods for location, translation, velocity, and progress (note that these work by calling locationInView: etc on self.view.superview, in case you are using the gesture recognizer to translate the view directly underneath itself).

NSLog(@"location: %f", gestureRecognizer.location);
NSLog(@"translation: %f", gestureRecognizer.translation);
NSLog(@"velocity: %f", gestureRecognizer.velocity);
NSLog(@"progress: %f", gestureRecognizer.progress);

✓ Delegate method for cancellation.

/* Cancels the gesture if it has moved less than 64 points, or if it is moving at less than 256 points per second */
- (BOOL)swipeGestureRecognizerShouldCancel:(CXSwipeGestureRecognizer *)gestureRecognizer
{
    return gestureRecognizer.translation < 64.0 && gestureRecognizer.velocity < 256.0;
}

✓ Delegate method for bouncing (returning YES causes the progress value to be halved, useful when emulating a UIScrollView-style bounce effect).

/* Bounces the gesture if it has moved backwards past its point of origin */
- (BOOL)swipeGestureRecognizerShouldBounce:(CXSwipeGestureRecognizer *)gestureRecognizer
{
    return gestureRecognizer.translation < 0.0;
}

Full API:

CXSwipeGestureRecognizerDelegate <UIGestureRecognizerDelegate>

- (void)swipeGestureRecognizerDidStart:(CXSwipeGestureRecognizer *)gestureRecognizer;
- (void)swipeGestureRecognizerDidUpdate:(CXSwipeGestureRecognizer *)gestureRecognizer;
- (void)swipeGestureRecognizerDidCancel:(CXSwipeGestureRecognizer *)gestureRecognizer;
- (void)swipeGestureRecognizerDidFinish:(CXSwipeGestureRecognizer *)gestureRecognizer;

- (BOOL)swipeGestureRecognizerShouldCancel:(CXSwipeGestureRecognizer *)gestureRecognizer;
- (BOOL)swipeGestureRecognizerShouldBounce:(CXSwipeGestureRecognizer *)gestureRecognizer;

CXSwipeGestureRecognizer : UIPanGestureRecognizer

@property (unsafe_unretained) id <CXSwipeGestureRecognizerDelegate> delegate;

- (CXSwipeGestureDirection)initialDirection;
- (CXSwipeGestureDirection)currentDirection;

- (CGFloat)location;
- (CGFloat)locationInDirection:(CXSwipeGestureDirection)direction;
- (CGFloat)locationInDirection:(CXSwipeGestureDirection)direction inView:(UIView *)view;

- (CGFloat)translation;
- (CGFloat)translationInDirection:(CXSwipeGestureDirection)direction;
- (CGFloat)translationInDirection:(CXSwipeGestureDirection)direction inView:(UIView *)view;

- (CGFloat)velocity;
- (CGFloat)velocityInDirection:(CXSwipeGestureDirection)direction;
- (CGFloat)velocityInDirection:(CXSwipeGestureDirection)direction inView:(UIView *)view;

- (CGFloat)progress;
- (CGFloat)progressInDirection:(CXSwipeGestureDirection)direction;
- (CGFloat)progressInDirection:(CXSwipeGestureDirection)direction inView:(UIView *)view;