swift - 每次旋转时 UIView 都会放错位置

Question

我在它下面有一个标尺(红色)和一个 UIView(橙色)，如下所示:

当我旋转标尺时，UIView 也会旋转，但它的位置不是我所期望的:

我用 UILongPressGestureRecognizer旋转尺子，当我握住手指并移动时，我得到一个angle重新绘制标尺，它工作得很好，但不适用于 UIView。
我如何创建和旋转 UIView:

 func createUIViewOutSideRuler(touchedPoint:CGPoint, notTouchedPoint:CGPoint, angle: CGFloat) -> UIView{
        let viewWidth = distanceFromTwoPoints(touchedPoint, notTouchedPoint)

        let view = UIView(frame: CGRect(x:notTouchedPoint.x, y: notTouchedPoint.y , width:  viewWidth, height: dotLineSize * 2))
        
        view.transform = CGAffineTransform(rotationAngle: angle);

        view.backgroundColor = .orange
        self.addSubview(view)
        return view
    }

根据 Sweeper 评论更新

let view = UIView(frame: CGRect(x:notTouchedPoint.x, y: notTouchedPoint.y , width:  viewWidth, height: dotLineSize * 2))
        
let vectorToStartPoint = CGPoint(x: view.center.x - touchedPoint.x,
                                         y: view.center.y - touchedPoint.y )
view.transform = CGAffineTransform(translationX: vectorToStartPoint.x, y: vectorToStartPoint.y)
                             .rotated(by: angle)
                             .translatedBy(x: -vectorToStartPoint.x, y: -vectorToStartPoint.y)

结果:
备注 : 我拖了 touchedPoint旋转
围绕 touchedPoint
围绕 notTouchedPoint

Answer 1

您需要围绕 notTouchedPoint 旋转 View .默认情况下，使用 CGAffineTransform.init(rotationAngle:) 创建的旋转将围绕其中心旋转 View 。
为此，首先将 View 的中心转换为 startPoint ，旋转它，然后将其平移回来。

let vectorToNotTouchedPoint = CGPoint(x: view.center.x - notTouchedPoint.x
                                      y: view.center.y - notTouchedPoint.y)
view.transform = CGAffineTransform(translationX: vectorToNotTouchedPoint.x, y: vectorToNotTouchedPoint.y)
                     .rotated(by: angle)
                     .translatedBy(x: -vectorToNotTouchedPoint.x, y: -vectorToNotTouchedPoint.y)