Rotating UIView after changing its AnchorPoint

Question

I have a media player in my app that persists across view controllers, and trying to let the user dismiss it as depicted in following picture:

I've added a UIPanGestureRecognizer to my player. When pan state changes I can calculate θ as below:

θ = Arctan(opposite/adjacent)

where adjacent is anchorPoint.x - initialTouchLocation.x, and opposite is translation.y

In my UIPanGestureRecognizer's UIGestureRecognizerStateBegan, I'm snapshotting player, setting snapshot's frame as the actual player's frame, adding that to the super view. Then I'm changing the snapshot's anchor point based on what's recommended here

And in UIGestureRecognizerStateChanged , I'm just calculating θ and rotating the snapshot accordingly.

here is the what I've got in UIPanGestureRecognizer action:

- (void)playerMovedDown:(UIPanGestureRecognizer *)recognizer {
    CGPoint translation = [recognizer translationInView:self.playerView];

    CCPlayer *playerView = (CCPlayer *) recognizer.view;
    switch (recognizer.state) {
        case UIGestureRecognizerStateBegan: {
            _adjacent = self.playerAnchorPoint.x - translation.x;


            self.playerSnapshot = [playerView snapshotViewAfterScreenUpdates:NO];
            [playerView.superview addSubview:self.playerSnapshot];
            self.playerSnapshot.frame = playerView.frame;

            [playerView.superview sendSubviewToBack:playerView];
            [playerView.superview bringSubviewToFront:self.playerSnapshot];


            [self setAnchorPoint:CGPointMake(self.playerOriginalFrame.size.width * relativePlayerAnchorPoint,
                0) forView:playerView];
        }

        case UIGestureRecognizerStateChanged : {
            _opposite = translation.y;
            CGFloat angel = atan2f(_opposite, _adjacent);
            self.playerSnapshot.transform = CGAffineTransformMakeRotation (-angel);
            NSLog(@"%@", NSStringFromCGRect(self.playerSnapshot.frame));
        }
        default: {

        }
    }
}

But once I'm trying to pan the player, the snapshot which should rotate on behalf of the actual view disappears.

I try finding player snapshot in Reveal , apparently it's added to the view hierarchy but I can't find it anywhere in the screen.

Just wondering if anyone can help me with fixing this, or pointing something out there about this issue.

Edit: I put NSLog(@"%@", NSStringFromCGRect(self.playerSnapshot.frame)); in my UIGestureRecognizerStateChanged after I'm applying rotate transform, and observed something that I cannot explain

{{7602.2540144175437, 34747.255839671474}, {353.40894445994036, 270.70438804942387}}
{{7677.5559653403761, 34908.541487295603}, {353.41127718399275, 271.19899878758588}}
{{7764.1261318069446, 35092.834523913771}, {353.41188643557598, 271.76320186068915}}
{{7801.1330694789358, 35171.252487591031}, {353.41147875381648, 272.00296155658725}}
{{7844.4014697306702, 35262.665288048178}, {353.41049980147181, 272.28221631572524}}

The origin of the player snapshot is moved way off the screen! But still I don't know why that's happening.

Answer 1

Figured that out, I was setting the anchorPoint incorrectly. I should have set that as a relative point like:

[self setAnchorPoint:CGPointMake(relativePlayerAnchorPoint, 0) forView:playerView];

and relativePlayerAnchorPoint = 0.8f