How to detect swipe direction?

Question

I would like to detect when a user makes a swipe gesture, and detect it's direction (left, right, up or down). I need to detect it not when the gesture is finished, but just when the iPhone knows the direction, even if it's not finished.

I am using XCode 5, and designing for iPhone 5 with iOS 7.

I would like to know the code that I have to paste to the .h, and to the .m, and if I have to drag and drop any item to the mainView.

Answer 1

If you want to know the direction when the gesture is not finished you would probably need the UIPanGestureRecognizer and detect the direction using the velocityInView: method.

in the *.h file:

@interface ViewController : UIViewController

@property (nonatomic, strong) UIPanGestureRecognizer *recognizer;

@end

in the *.m file:

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGesture:)];

    [self.view addGestureRecognizer:self.recognizer];
}

-(void)panGesture:(UIPanGestureRecognizer *)sender
{
    NSLog(@"Velocity: %@", NSStringFromCGPoint([sender velocityInView:self.view]));

    // Here You need to determine the direction
}
@end