顺时针旋转UIImageView [英] Rotate UIImageView clockwise

问题描述

这应该很简单，但是我无法将 UIImageView 旋转360度，一直重复一次。

This should be simple, but I'm having trouble rotating a UIImageView a full 360 degrees, repeated forever.

[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveLinear | UIViewAnimationOptionBeginFromCurrentState animations:^{
    self.reloadButton.imageView.transform = CGAffineTransformRotate(self.reloadButton.imageView.transform, -M_PI);
} completion:^(BOOL finished) {

}];

根据文档，我传递给 CGAffineTransformRotate 确定旋转的方向，但是上面的代码逆时针旋转。与 M_PI 相同。

According to the docs, the signedness of the angle I pass to CGAffineTransformRotate determines the direction of the rotation, but the above code rotates counterclockwise. Same with M_PI.

矩阵旋转的角度（以弧度为单位）坐标
系统轴。在iOS中，正值指定逆时针
旋转，负值指定顺时针旋转。在Mac OS
X中，正值指定顺时针旋转，而负值
指定逆时针旋转。

The angle, in radians, by which this matrix rotates the coordinate system axes. In iOS, a positive value specifies counterclockwise rotation and a negative value specifies clockwise rotation. In Mac OS X, a positive value specifies clockwise rotation and a negative value specifies counterclockwise rotation.

推荐答案

Christoph已经按照正确的方式进行操作，但是还有一种更好的方法来使它保持旋转，而无需在每次结束时在动画委托中重新调用它。这是完全错误的。

Christoph is already going the correct way, but there is a far better way to keep it spinning without reinvoke it in the animation delegates every time it ends. This is simply wrong.

只需将动画的repeatCount属性设置为 HUGE_VALF 。

Just set the repeatCount property of your animation to HUGE_VALF.

CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
animation.fromValue = @0.0f;
animation.toValue = @(2*M_PI);
animation.duration = 0.5f;             // this might be too fast
animation.repeatCount = HUGE_VALF;     // HUGE_VALF is defined in math.h so import it
[self.reloadButton.imageView.layer addAnimation:animation forKey:@"rotation"];

如，这将使动画永远重复。

As stated in the documentation, this will cause the animation to repeat forever.

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