Question

I’m trying these two methods to move and rotate an UIView. Both methods work separately but if I rotate and then move the UIView it disappears.

- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {


CGRect rect = self.aView.frame;

UITouch *touch = [touches anyObject];

CGPoint pPoint = [touch previousLocationInView:self.view];
CGPoint cPoint = [touch locationInView:self.view];

float deltaX = cPoint.x - pPoint.x;
float deltaY = cPoint.y - pPoint.y;

rect.origin.x = rect.origin.x + deltaX;
rect.origin.y = rect.origin.y + deltaY;

self.aView.frame = rect;

}
- (void)rotate:(UIRotationGestureRecognizer *) recognizer {

    CGFloat rotation = angle + recognizer.rotation;

    NSLog(@"%f", angle * 180 / M_PI);

    self.aView.transform = CGAffineTransformMakeRotation (rotation);

    if (recognizer.state == UIGestureRecognizerStateEnded) 
        angle = rotation;

}

Answer 1

Gesture recognisers take priority over touchMoved, so it’s hard to use them both with the same view.

Use a UIPanGestureRecognizer instead of touchMoved to handle dragging the UIView. You can then get the UIPanGestureRecognizer and UIRotationGestureRecognizer to cooperate with one another by implementing the

– gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer:

method, which is defined in the UIGestureRecognizerDelegate protocol.