ios - CGAffineTransformMakeRotation 再次不起作用

Question

我创建了一个 UIView 并将其图层的内容设置为图像。我在这个 View 中添加了一个点击手势。当我点击 View 时，我希望它旋转 180 度，当我单击关闭按钮时，我希望它旋转到原来的度数。但是当我尝试旋转它时它不起作用。

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIImage *image = [UIImage imageNamed:@"menuArray"];
    self.menuView.layer.contents = (__bridge id)image.CGImage;

    self.menuView.userInteractionEnabled = YES;
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap)];
    [self.menuView addGestureRecognizer:tap];
}
//rotate it 180 degree
- (void)tap
{
    [UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionBeginFromCurrentState|UIViewAnimationOptionCurveEaseIn animations:^{
        self.menuView.layer.affineTransform = CGAffineTransformMakeRotation(M_PI);
    } completion:^(BOOL finished) {

    }];
}
//rotate it back. this won't work. I have change the value from M_PI to M_PI_2, M_PI_4. it's not working.
- (IBAction)close:(id)sender
{
    [UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionBeginFromCurrentState|UIViewAnimationOptionCurveEaseIn animations:^{
        self.menuView.layer.affineTransform = CGAffineTransformMakeRotation(-M_PI);
    } completion:^(BOOL finished) {

    }];
}

Answer 1

要撤消 affineTransorm，您应该将其设置为常量 affineTransformIdentity ，可以说是 nil 的变换，一个全零矩阵。

所以在你想要旋转的第二种方法中设置self.menuView.layer.affineTransform = CGAffineTransformIdentity