旋转与iPhone中的触摸拖动相对应的图像 [英] Rotate the image corresponding to the touch drag in iPhone

问题描述

我想顺时针或逆时针旋转图像，以使其与用户触摸拖动相对应。我认为可以通过一些数学和逻辑来完成。

I want to rotate the image in clockwise or anticlockwise direction corresponding to the user touch drag with its speed. I think this can be done with some math and logic. What would a code sample for this look like?

推荐答案

如果目标是iOS 3.2或更高版本，则可以使用 UIRotationGestureRecognizer 。代码看起来像这样：

If you're targeting iOS 3.2 or greater, you can use UIRotationGestureRecognizer. The code would look something like this:

在您的设置方法中（ viewDidLoad 或 init 等）：

In your setup method (viewDidLoad or init, etc,):

UIRotationGestureRecognizer *rotationGesture = 
  [[UIRotationGestureRecognizer alloc] initWithTarget:self
                                               action:@selector(handleRotate:)];
rotationGesture.delegate = self;
[myImageView addGestureRecognizer:rotationGesture];
[rotationGesture release];

事件处理程序：

- (void)handleRotate:(UIRotationGestureRecognizer *)recognizer {
  if(recognizer.state == UIGestureRecognizerStateBegan || 
     recognizer.state == UIGestureRecognizerStateChanged)
  {
    recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, 
                                                        recognizer.rotation);
    [recognizer setRotation:0];
  }
}

我还有更多的手势识别器示例（包括上面的一个）在 github 上。

I have some more examples of gesture recognizers (including the one above) on github.

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