使用 CGAfffineTransformRotate 旋转视图

问题描述

我有一个要旋转的圆形图像，这样黄色和黑色的条纹圆圈就会停留在用户的手指下方并在两个方向上旋转.到目前为止我有这个:

I have a circular image which I am trying to rotate, so that the yellow and black striped circle stays under the user's finger and rotates in both directions. I have this so far:

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

    UIView *shuttle = [recognizer view];

    if ([recognizer state] == UIGestureRecognizerStateBegan ||
        [recognizer state] == UIGestureRecognizerStateChanged) {

        [recognizer view].transform = CGAffineTransformRotate([[recognizer view] transform],M_PI / 20.0f);
        [recognizer setTranslation:CGPointZero inView:[shuttle superview]];
    }
}

此外，目前，最轻微的移动都会导致视图旋转一整圈，这显然是不希望的.

Also, currently, the slightest movement can cause the view to rotate in a full circle, which is obviously not desired.

推荐答案

我怀疑这个方法被调用了很多.尝试使用 NSLog 并检查它做了多少次.无论如何，您没有正确计算角度，您可以尝试使用

I suspect this method gets called A LOT. Try using NSLog and check how many time it does. Anyway, you are not calculating the angle properly, you could try using

-(CGPoint)translationInView:(UIView *)view

从识别器中计算出正确的旋转角度.

from the recognizer to calculate the correct angle to rotate.

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