CABasicAnimation 在 x 轴上旋转视图

Question

我需要将我的视图在 x 轴上旋转 180 度。旋转完成，但当它开始旋转时，它会折叠我的半视图。这是我所做的代码可以帮助任何人。

        CABasicAnimation* rotationAnimation;
        rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.x"];
        rotationAnimation.fromValue = [NSNumber numberWithFloat:0]; 
        rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2.0];   
        rotationAnimation.duration = 2.0;
        rotationAnimation.cumulative = YES;
        rotationAnimation.repeatCount = 0;
        [_view_topShowDate.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];

Answer 1

您必须最好在 viewDidLoad 或动画开始之前的某个地方设置锚点。默认情况下，它会将 anchorPoint 设为 (0.5,0.5)，因此您会看到从中心开始的旋转。

_viewToRotate.layer.anchorPoint = CGPointMake(0.5, 1.0);

然后调用基本的动画方法。

阅读更多http://ronnqvi.st/about-the-anchorpoint/

当您更改锚点时，它会移动图层的位置。 要重新定位它，请使用以下内容

-(void)setNewAnchorPoint:(CGPoint)anchorPoint forView:(UIView *)view
{
    CGPoint newPoint = CGPointMake(view.bounds.size.width * anchorPoint.x, view.bounds.size.height * anchorPoint.y);
    CGPoint oldPoint = CGPointMake(view.bounds.size.width * view.layer.anchorPoint.x, view.bounds.size.height * view.layer.anchorPoint.y);

    newPoint = CGPointApplyAffineTransform(newPoint, view.transform);
    oldPoint = CGPointApplyAffineTransform(oldPoint, view.transform);

    CGPoint position = view.layer.position;

    position.x -= oldPoint.x;
    position.x += newPoint.x;

    position.y -= oldPoint.y;
    position.y += newPoint.y;

    view.layer.position = position;
    view.layer.anchorPoint = anchorPoint;
}