objective-c – 顺时针旋转UIImageView

发布时间：2020-12-16 05:56:48 所属栏目：百科来源：网络整理

导读：这应该很简单,但是我无法使UI ImageView完整360度旋转,永远重复. [UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveLinear | UIViewAnimationOption

这应该很简单,但是我无法使UI ImageView完整360度旋转,永远重复.

[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的角度的有符号决定了旋转的方向,但上述代码逆时针旋转.与M_PI相同.

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.

解决方法

Christoph已经走了正确的道路,但是有一个更好的方法来保持它的旋转,而不会在动画代表中每次都结束时重新启动它.这是错误的.

只需将动画的repeatCount属性设置为HUGE_VALF即可.

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in the documentation所述,这将导致动画永远重复.

（编辑：李大同）

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