objective-c - 顺时针旋转 UIImageView

Question

这应该很简单，但我无法旋转UIImageView一个完整的 360 度，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，我传递的角度的符号CGAffineTransformRotate决定了旋转的方向，但上面的代码逆时针旋转。与相同M_PI。

该矩阵旋转坐标系轴的角度（以弧度为单位）。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，负值指定逆时针旋转。

score 14 · Accepted Answer

Christoph 已经走上了正确的道路，但是有一种更好的方法可以让它保持旋转，而无需在每次结束时在动画代理中重新调用它。这是完全错误的。

只需将动画的 repeatCount 属性设置为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.

score 1 · Accepted Answer

抱歉错过了第一部分，视图使用较小的角度旋转得很好：

[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionAllowUserInteraction | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveLinear | UIViewAnimationOptionBeginFromCurrentState animations:^{
        redView.transform = CGAffineTransformRotate(redView.transform, M_PI_2);
    } completion:^(BOOL finished) {

    }];

我找不到任何有意义的解释为什么它会因 M_PI 而失败。

score 1 · Accepted Answer

不久前我遇到了同样的问题。我不记得这个问题的原因，但这是我的解决方案：

/**
 * Incrementally rotated the arrow view by a given angle.
 *
 * @param degrees Angle in degrees.
 * @param duration Duration of the rotation animation.
 */
- (void)rotateArrowViewByAngle:(CGFloat)degrees
                  withDuration:(NSTimeInterval)duration {

    CABasicAnimation *spinAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    spinAnimation.fromValue = [NSNumber numberWithFloat:self.currentAngle / 180.0 * M_PI];
    spinAnimation.toValue = [NSNumber numberWithFloat:degrees / 180.0 * M_PI];
    spinAnimation.duration = duration;
    spinAnimation.cumulative = YES;
    spinAnimation.additive = YES;
    spinAnimation.removedOnCompletion = NO;
    spinAnimation.delegate = self;
    spinAnimation.fillMode = kCAFillModeForwards;

    [self.arrowView.layer addAnimation:spinAnimation forKey:@"spinAnimation"];

    self.currentAngle = degrees;
}

然后你可以使用委托方法

- (void)animationDidStart:(CAAnimation *)theAnimation
- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag

旋转保持旋转。此外，程度和持续时间参数可能是非常高的数字......如果这足够了。

更新：
正如银口所说，

spinAnimation.repeatCount = HUGE_VALF;     // HUGE_VALF is defined in math.h so import it

比在委托中重新启动动画要好得多。

请注意：
self.currentAngle 是一个记住当前最终旋转的属性。
我需要它来使视图左右旋转。

score 1 · Accepted Answer

I wrote UIImageView category for this: https://gist.github.com/alexhajdu/5658543.

Just use:

[_myImageView rotate360WithDuration:1.0 repeatCount:0]; //0 for infinite loop

objective-c - 顺时针旋转 UIImageView

4 回答 4

Related

Reference