When Rotating UIImageView The Image Moves Off Screen/Out of View

Question

I've got a view on screen with a UIImageView inside it. The user can pan, scale, and rotate.

I have a rotation gesture setup, and everything is fine with rotation except for when rotating the image moves off the screen/out of the view.

Any idea what would cause this to behavior? The expected behavior I'm looking for is when you rotate the image it does not move at all (other than rotating).

I've tried setting an anchor point of the layer of the parent view, but it doesn't seem to be helping any.

EDIT: I've put some logging on the rotation gesture and what's happening is the image views center (X) is what is getting off hence it going off the screen.

Why would this coordinate change upon rotation? The Y is staying the same. I've even tried turning the other gestures off and it's definitely something whacky with the rotation gesture.

Code Below:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    CALayer *l = [self.viewCase layer];
    [l setMasksToBounds:YES];
    [l setCornerRadius:30.0];

    self.imgUserPhoto.userInteractionEnabled = YES;
    [self.imgUserPhoto setClipsToBounds:NO];

    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panDetected:)];
    panRecognizer.maximumNumberOfTouches = 1;
    [self.view addGestureRecognizer:panRecognizer];

    UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchDetected:)];
    [self.view addGestureRecognizer:pinchRecognizer];

    UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotationDetected:)];
    [self.view addGestureRecognizer:rotationRecognizer];

    UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapDetected:)];
    tapRecognizer.numberOfTapsRequired = 2;
    [self.view addGestureRecognizer:tapRecognizer];

    panRecognizer.delegate = self;
    pinchRecognizer.delegate = self;
    rotationRecognizer.delegate = self;
}

- (void)panDetected:(UIPanGestureRecognizer *)panRecognizer
{
    CGPoint translation = [panRecognizer translationInView:self.view];
    CGPoint imageViewPosition = self.imageView.center;
    imageViewPosition.x += translation.x;
    imageViewPosition.y += translation.y;

    self.imageView.center = imageViewPosition;
    [panRecognizer setTranslation:CGPointZero inView:self.view];
}

- (void)pinchDetected:(UIPinchGestureRecognizer *)pinchRecognizer
{
    CGFloat scale = pinchRecognizer.scale;
    self.imageView.transform = CGAffineTransformScale(self.imageView.transform, scale, scale);
    pinchRecognizer.scale = 1.0;
}

- (void)rotationDetected:(UIRotationGestureRecognizer *)rotationRecognizer
{
    CGFloat angle = rotationRecognizer.rotation;
    self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, angle);
    rotationRecognizer.rotation = 0.0;
}

- (void)tapDetected:(UITapGestureRecognizer *)tapRecognizer
{
    [UIView animateWithDuration:0.25 animations:^{
        self.imageView.center = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds));
        self.imageView.transform = CGAffineTransformIdentity;
    }];
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

Answer 1

也许是因为泛姿态也越来越称为：尝试设置maximumNumberOfTouches您到1 UIPanGestureRecognizer