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