如何动画旋转并将UIView移动到其原始位置？

Question

我有一个UIImageView与平移手势识别器，我移动和基于用户操作旋转。 当用户提起手指，我希望它是动画回到原来的位置，这里是我的代码：

- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer { 

    if (recognizer.state == UIGestureRecognizerStateBegan) { 
     startX = recognizer.view.center.x; 
     startY = recognizer.view.center.y; 
     startRotation = atan2(recognizer.view.transform.b, recognizer.view.transform.a); 
     NSLog(@"Start Position %f %f %f", startX, startY, startRotation); 
    } else if (recognizer.state == UIGestureRecognizerStateEnded) { 

     float distance = (startX - recognizer.view.center.x)/DISTANCE_TO_ACCEPT; 
     CGPoint center = recognizer.view.center; 


      // animate back 
      [UIView animateWithDuration:0.5 animations:^{ 
       NSLog(@"Position %f %f %f", recognizer.view.center.x, recognizer.view.center.y, atan2(recognizer.view.transform.b, recognizer.view.transform.a)); 
       NSLog(@"Destination %f %f %f", startX, startY, startRotation); 
       NSLog(@"Translation %f %f %f", startX - center.x, startY - center.y, (startRotation - atan2(recognizer.view.transform.b, recognizer.view.transform.a))); 

       recognizer.view.transform = CGAffineTransformRotate(CGAffineTransformTranslate(recognizer.view.transform, startX - center.x, startY - center.y), (CGFloat) (startRotation - atan2(recognizer.view.transform.b, recognizer.view.transform.a))); 
      }]; 


    } else if (recognizer.state == UIGestureRecognizerStateChanged) { 
     // move image 
     CGPoint translation = [recognizer translationInView:self.view]; 
     recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y); 
     [recognizer setTranslation:CGPointMake(0, 0) inView:self.view]; 

     // rotate image 
     float distance = (startX - recognizer.view.center.x)/DISTANCE_TO_ACCEPT; 

     // cap distance 
     if (distance > 1) { 
      distance = 1; 
     } else if (distance < -1) { 
      distance = -1; 
     } 

     double rotation = 15 - startRotation; 
     rotation = rotation * distance; 
     recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, (CGFloat) ((rotation * M_PI/180) - atan2(recognizer.view.transform.b, recognizer.view.transform.a))); 

    } 

} 

但它从来就没有到原来的位置。它总是有某种抵消。图像视图的进一步移动只会使情况变得更糟。 它看起来像在回放动画期间不会修改位置，因为当我再次平移图像时，开始位置和旋转等于它在上次移动结束时的位置和旋转[即使在屏幕上图像位置并且旋转已经改变]。

我在这里做错了什么？

感谢

Answer 1

尝试这样的事情在UIGestureRecognizerStateEnded状态：

recognizer.view.transform = CGAffineTransformIdentity; 
recognizer.view.center = CGPointMake(startX,startY);