What happens when dragging off screen?

Question

I have an object that can be dragged around. Once the user's finger goes off screen and comes back, I loose the ability to drag the object. If the user then does another touch and drag, everything is fine.

How can I get notified once the user's finger drags back onto the screen? Since touchesBegan doesn't fire, I don't get any notification.

Here is my touchesMoved, which I call in the touchesBegan:

- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];

    //stop object dragging at edge of screen
if(location.x > 35){
 myboject.center = location;}
}

Answer 1

The described behaviour seems normal to me, and all built-in Apple apps behave the same way. Since there’s no touch screen outside of the touch screen (yep), I believe there’s no way the device can distinguish between touch beginning or moving from outside of the screen.