How to add a vertical swipe gesture to iPhone app for all screens?

Question

I\'d like to add a gesture to my app so when the user swipes vertically it triggers a method to do something. The swipe can be up or down. I\'ve never done anything with g

Answer 1

This goes in ApplicationDidLaunch:

UISwipeGestureRecognizer *swipeGesture = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipedScreen:)] autorelease];
swipeGesture.numberOfTouchesRequired = 2;
    swipeGesture.direction = (UISwipeGestureRecognizerDirectionUp|UISwipeGestureRecognizerDirectionDown);

[window addGestureRecognizer:swipeGesture];

then implement

- (void) swipedScreen:(UISwipeGestureRecognizer*)swipeGesture {
   // do stuff
}

Use the documentation for UIGestureRecognizer and UISwipeGestureRecognizer.

Also if you wish to detect the direction of the swipe you will have to setup two separate gesture recognizers. You can not get the direction of a swipe from a swipe gesture recognizer, only the directions it is registered to recognize.

Answer 2

In swift 4.0, that goes on the method didFinishLaunchingWithOptions of the AppDelegate:

let swipeGesture = UISwipeGestureRecognizer(target: self, action: #selector(self.swipedScreen(swipeGesture:)))
swipeGesture.numberOfTouchesRequired = 2
swipeGesture.direction = [UISwipeGestureRecognizerDirection.up,  UISwipeGestureRecognizerDirection.down]
window?.addGestureRecognizer(swipeGesture)

And the action:

@objc func swipedScreen(swipeGesture: UISwipeGestureRecognizer){
    Swift.print("hy")
}