画像を回転させると突然表示されます

次のコードを使用して、左と右の矢印でジェスチャーを開始して画像を回転します。画像を回転させると突然表示されます

- (void)handleRotation:(UIPanGestureRecognizer *)recognizer 
{ 

UIView* cview = self.superview.superview; 

UIView* lView = self.superview; 

CGPoint origin = [lView convertPoint: self.center toView: cview]; 

if (recognizer.state == UIGestureRecognizerStateBegan) 
{ 
    if (recognizer.view == leftImage) 
    { 
     initialP= [self convertPoint: leftImage.center toView: cview]; 
    } 
    else 
    { 
     initialP = [self convertPoint: rightImage.center toView: cview]; 
    } 
} 
CGPoint currentP = [recognizer translationInView:cview]; 
currentP.x += initialP.x; 
currentP.y += initialP.y; 

CGFloat angle = 0; 


CGFloat a = initialP.x - origin.x; 
CGFloat b = initialP.y - origin.y; 
CGFloat c = currentP.x - origin.x; 
CGFloat d = currentP.y - origin.y; 
angle = acosf(((a*c) + (b*d))/((sqrt(a*a + b*b)) * (sqrt(c*c + d*d)))); 


angle += lastReleasedAngle; 

if (currentP.y < (currentP.x *(initialP.y - origin.y) + (initialP.x * origin.y - initialP.y * origin.x))/(initialP.x - origin.x)) 
{ 
    angle = -angle; 
} 

if (recognizer.view == leftImage) 
{ 
    angle = -angle; 
} 

if(recognizer.state == UIGestureRecognizerStateBegan || 
    recognizer.state == UIGestureRecognizerStateChanged || recognizer.state == UIGestureRecognizerStateEnded) 
{ 

    [self setTransform: CGAffineTransformMakeRotation(angle)]; 
} 
if (recognizer.state == UIGestureRecognizerStateEnded) 
{ 

    lastReleasedAngle = angle; 
}

それは私がここから回転を開始し、それは私がしようと、その後どこか他の回転を解放fine.Whenの作品ここにリリースnow..when fine.Say、右矢印が0度である完璧に動作回転を開始まず時間を180度回転させた後、画像は180度回転し始めます。