iOS:通过CATransform3DRotate旋转时跳转uiview

Question

我尝试用自己的锚点旋转一个90度角的uiview (高度和宽度为100)。更改锚点后，我转换我的视图，以便两个更改相互抵消。

当我使用(Double.pi)旋转视图时，它会像预期的那样产生动画效果，但当我更改为(Double.pi/2)时，视图会向上跳跃。

    testView.layer.anchorPoint = CGPoint(x: 0.5, y: 1)
    testView.layer.transform = CATransform3DMakeTranslation(0, -50, 0)

    UIView.animate(withDuration: 2.3, delay: 0, options: .curveLinear, animations: { () -> Void in
        var allTransofrom = self.testView.layer.transform
        var c3d = CATransform3DIdentity
        c3d.m34 = 2.5 / (2000)
        let rot = CATransform3DRotate(c3d, CGFloat(Double.pi/2), 1, 0, 0)
        allTransofrom = CATransform3DConcat(allTransofrom, rot)
        self.testView.layer.transform = allTransofrom
    }, completion: {(finished) in
    } )

完整代码here