Question

每次拖动时我都会将视图旋转45度。这是我的代码。这里的问题是视图只旋转一次。之后没有轮换。会是什么原因？任何帮助

  - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
      CGContextRef context = UIGraphicsGetCurrentContext();
      [UIView beginAnimations:nil context:context];
      [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
      [UIView setAnimationDuration:0];
      dialView.transform = CGAffineTransformMakeRotation(45* M_PI/180);
      [UIView commitAnimations];
   }

Answer 1

您还可以使用CGAffineTransformRotate从其现有transform进行轮播，如下所示：

dialView.transform = CGAffineTransformRotate(dialView.transform, 45 * M_PI / 180);

Answer 2

旋转始终相对于0.如果多次旋转x，它将仅在第一次旋转。如果你想在每次调用该代码时旋转45，你需要有一个计数器，它看起来像这样：

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
  step++;//You are supposed to keep this variable global.
  CGContextRef context = UIGraphicsGetCurrentContext();
  [UIView beginAnimations:nil context:context];
  [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
  [UIView setAnimationDuration:0];
  dialView.transform = CGAffineTransformMakeRotation(45*step* M_PI/180);
  [UIView commitAnimations];

}

在touchesMoved中查看旋转

2 个答案: