iOS 360度无限旋转

Question

我有这个代码可以无限旋转 UIImageView

            [UIView animateWithDuration:0.3f
                                  delay:0.0f
                                options:UIViewAnimationOptionCurveLinear|UIViewAnimationOptionRepeat
                             animations: ^{
                                 self.spinner.transform = CGAffineTransformRotate(CGAffineTransformIdentity, -M_PI);
                             }
                             completion: ^(BOOL finished) {
                             }];

但是我首先称这个方法为图像，它顺时针旋转而不是逆时针旋转。如果我在图像旋转时重新调用此方法，它会改变方向并开始逆时针旋转。

想法？

Answer 1

来自文档：

In iOS, a positive value specifies counterclockwise rotation and a negative value specifies clockwise rotation.

  CGAffineTransformRotate(CGAffineTransformIdentity, -M_PI)

更新： M_PI 是常量，不受负值影响。不知何故 -M_PI 最后还是被当成正数了！！！

如果你给-180它会顺时针旋转，如果你给180它会逆时针旋转

Answer 2

改用 CABasicAnimation，因为它更强大。您只需调用以下代码片段一次，动画将运行无限期地运行：

CABasicAnimation *rotate = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
rotate.toValue = @(M_PI * 2); // use @(-M_PI * 2) for counter clockwise
rotate.duration = 0.3;
rotate.cumulative = true;
rotate.repeatCount = HUGE_VALF;
[self.spinner.layer addAnimation:rotate forKey:@"rotateAnim"];

Swift:

let rotate = CABasicAnimation(keyPath: "transform.rotation.z")
rotate.toValue = M_PI * 2
rotate.duration = 0.3
rotate.cumulative = true
rotate.repeatCount = HUGE
self.spinner.layer.addAnimation(rotate, forKey: "rotateAnim")

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