将UIButton旋转180度并将其旋转回来

Question

我有UIButton,我希望在一个方向旋转180度,然后再旋转180度.我一直在做动画一段时间使用CABasicAnimation,但这次我想用变换来做.这是我写的代码:

- (IBAction)blurAction:(id)sender {
    if (self.blurActive) {
        [UIView animateWithDuration:0.1 animations:^{
            self.blurView.alpha = 0;
            self.blurButton.transform = CGAffineTransformMakeRotation(M_PI);
        } completion:^(BOOL finished) {
            self.blurActive = NO;
        }];
    }
    else {
        [UIView animateWithDuration:0.1 animations:^{
            self.blurView.alpha = 1;
            self.blurButton.transform = CGAffineTransformMakeRotation(-M_PI);
        } completion:^(BOOL finished) {
            self.blurActive = YES;
        }];
    }
}

它第一次工作,但第二次按下按钮,没有任何反应.有人可以解释我在这里做错了什么吗？

Answer 1

实现此效果的最简单方法是旋转小于180°的微小量:

- (IBAction)toggle:(UIButton *)sender {
    [UIView animateWithDuration:0.2 animations:^{
        if (CGAffineTransformEqualToTransform(sender.transform, CGAffineTransformIdentity)) {
            sender.transform = CGAffineTransformMakeRotation(M_PI * 0.999);
        } else {
            sender.transform = CGAffineTransformIdentity;
        }
    }];
}

结果:

Answer 2

这是@rob mayoff解决方案的Swift3代码.

UIView.animate(withDuration:0.1, animations: { () -> Void in
    if sender.transform == .identity {
        sender.transform = CGAffineTransform(rotationAngle: CGFloat(M_PI * 0.999))
    } else {
        sender.transform = .identity
    }
})

Swift4

M_PI 已弃用并替换为 Double.pi

UIView.animate(withDuration:0.1, animations: { () -> Void in
    if  sender.transform == .identity {
        sender.transform = CGAffineTransform(rotationAngle: CGFloat(Double.pi * 0.999))
    } else {
        sender.transform = .identity
    }
})

Answer 3

M_PI并且-M_PI将具有相同的视觉效果

转回原来的位置应该是

self.blurButton.transform = CGAffineTransformMakeRotation(0);

- 编辑 -

要为逆时针旋转设置动画,您可以使用 -2*M_PI

self.blurButton.transform = CGAffineTransformMakeRotation(-2*M_PI);