我想更改anchorPoint，但将视图保留在同一位置。我已经尝试过NSLog-ing self.layer.position，self.center并且无论如何更改anchorPoint，它们都保持不变。但是我的观点动了！

有关如何执行此操作的任何提示？

self.layer.anchorPoint = CGPointMake(0.5, 0.5);
NSLog(@"center point: %f %f", self.layer.position.x, self.layer.position.y);
self.layer.anchorPoint = CGPointMake(1, 1);
NSLog(@"center point: %f %f", self.layer.position.x, self.layer.position.y);

输出为：

2009-12-27 20:43:24.161 Type[11289:207] center point: 272.500000 242.500000
2009-12-27 20:43:24.162 Type[11289:207] center point: 272.500000 242.500000

《核心动画编程指南》的“ 层几何和变换”部分介绍了CALayer的位置和anchorPoint属性之间的关系。基本上，图层的位置是根据图层的anchorPoint的位置指定的。默认情况下，图层的anchorpoint为（0.5，0.5），位于图层的中心。设置图层的位置时，然后要在其上层的坐标系中设置图层中心的位置。

由于位置相对于图层的anchorPoint，因此在保持相同位置的同时更改该anchorPoint将移动图层。为了防止这种移动，您需要调整图层的位置以考虑新的anchorPoint。我执行此操作的一种方法是，获取图层的边界，将边界的宽度和高度乘以新旧的anchorPoint的归一化值，取两个anchorPoints的差，并将该差应用于图层的位置。

您甚至可以通过CGPointApplyAffineTransform()与UIView的CGAffineTransform一起使用来解决这种轮换问题。

我有同样的问题。即使旋转视图，布拉德·拉尔森（Brad Larson）的解决方案也能很好地工作。这是他的解决方案翻译为代码。

-(void)setAnchorPoint:(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;
}

和快速等效：

func setAnchorPoint(anchorPoint: CGPoint, forView view: UIView) {
    var newPoint = CGPointMake(view.bounds.size.width * anchorPoint.x, view.bounds.size.height * anchorPoint.y)
    var 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)

    var 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
}

SWIFT 4.x

func setAnchorPoint(anchorPoint: CGPoint, forView view: UIView) {
    var newPoint = CGPoint(x: view.bounds.size.width * anchorPoint.x,
                           y: view.bounds.size.height * anchorPoint.y)


    var oldPoint = CGPoint(x: view.bounds.size.width * view.layer.anchorPoint.x,
                           y: view.bounds.size.height * view.layer.anchorPoint.y)

    newPoint = newPoint.applying(view.transform)
    oldPoint = oldPoint.applying(view.transform)

    var 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
}

解决此问题的关键是使用frame属性，这是唯一奇怪的更改。

迅捷2

let oldFrame = self.frame
self.layer.anchorPoint = CGPointMake(1, 1)
self.frame = oldFrame

迅捷3

let oldFrame = self.frame
self.layer.anchorPoint = CGPoint(x: 1, y: 1)
self.frame = oldFrame

然后，我进行调整大小，使其从anchorPoint缩放。然后，我必须还原旧的anchorPoint；

迅捷2

let oldFrame = self.frame
self.layer.anchorPoint = CGPointMake(0.5,0.5)
self.frame = oldFrame

迅捷3

let oldFrame = self.frame
self.layer.anchorPoint = CGPoint(x: 0.5, y: 0.5)
self.frame = oldFrame

编辑：如果旋转视图，此效果会消失，因为如果已应用CGAffineTransform，则frame属性未定义。

对我来说position，这anchorPoint是最容易的，当我将其与我对UIView中frame.origin的理解进行比较时，这是最简单的。一个带有frame.origin =（20,30）的UIView意味着该UIView从其父视图的左边向左20点，从顶部向顶部30点。此距离是从UIView的哪一点算起的？从UIView的左上角计算得出。

在图层anchorPoint标记中，从该点计算该距离（以标准化形式，即0到1），因此例如layer.position =（20，30）表示该图层anchorPoint是从其父图层的左起20个点，而从其父图层的顶部起是30个点。默认情况下，图层anchorPoint为（0.5，0.5），因此距离计算点位于图层中心。下图将有助于阐明我的观点：

anchorPoint 如果您将变换应用于图层，也恰好是旋转将发生的点。

有一个简单的解决方案。这是基于肯尼的答案。但是，与其应用旧框架，不如使用其原点和新框架来计算翻译，然后将该翻译应用于中心。它也适用于旋转视图！这是代码，比其他解决方案简单得多：

func setAnchorPoint(anchorPoint: CGPoint, view: UIView) {
   let oldOrigin = view.frame.origin
   view.layer.anchorPoint = anchorPoint
   let newOrigin = view.frame.origin

   let translation = CGPoint(x: newOrigin.x - oldOrigin.x, y: newOrigin.y - oldOrigin.y)

   view.center = CGPoint(x: view.center.x - translation.x, y: view.center.y - translation.y)
}

对于那些需要它的人，这是Magnus在Swift中的解决方案：

func setAnchorPoint(anchorPoint: CGPoint, view: UIView) {
    var newPoint: CGPoint = CGPointMake(view.bounds.size.width * anchorPoint.x, view.bounds.size.height * anchorPoint.y)
    var oldPoint: CGPoint = 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)

    var position: CGPoint = view.layer.position

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

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

    view.setTranslatesAutoresizingMaskIntoConstraints(true)     // Added to deal with auto layout constraints
    view.layer.anchorPoint = anchorPoint
    view.layer.position = position
}

这是user945711的答案，已针对OS X上的NSView进行了调整。除了NSView没有.center属性外，NSView的框架没有更改（可能是因为NSViews默认不带有CALayer），但是当更改了anchorPoint时，CALayer框架的原点也发生了变化。

func setAnchorPoint(anchorPoint: NSPoint, view: NSView) {
    guard let layer = view.layer else { return }

    let oldOrigin = layer.frame.origin
    layer.anchorPoint = anchorPoint
    let newOrigin = layer.frame.origin

    let transition = NSMakePoint(newOrigin.x - oldOrigin.x, newOrigin.y - oldOrigin.y)
    layer.frame.origin = NSMakePoint(layer.frame.origin.x - transition.x, layer.frame.origin.y - transition.y)
}

如果更改anchorPoint，其位置也会改变，除非您的原点为零点CGPointZero。

position.x == origin.x + anchorPoint.x;
position.y == origin.y + anchorPoint.y;

在情节提要板上编辑并查看UIView的锚点（快速3）

这是一种替代解决方案，它允许您通过Attributes Inspector更改锚点，并具有另一个属性来查看锚点以进行确认。

创建新文件以包含在您的项目中

import UIKit

@IBDesignable
class UIViewAnchorPoint: UIView {

    @IBInspectable var showAnchorPoint: Bool = false
    @IBInspectable var anchorPoint: CGPoint = CGPoint(x: 0.5, y: 0.5) {
        didSet {
            setAnchorPoint(anchorPoint: anchorPoint)
        }
    }

    override func draw(_ rect: CGRect) {
        if showAnchorPoint {
            let anchorPointlayer = CALayer()
            anchorPointlayer.backgroundColor = UIColor.red.cgColor
            anchorPointlayer.bounds = CGRect(x: 0, y: 0, width: 6, height: 6)
            anchorPointlayer.cornerRadius = 3

            let anchor = layer.anchorPoint
            let size = layer.bounds.size

            anchorPointlayer.position = CGPoint(x: anchor.x * size.width, y: anchor.y * size.height)
            layer.addSublayer(anchorPointlayer)
        }
    }

    func setAnchorPoint(anchorPoint: CGPoint) {
        var newPoint = CGPoint(x: bounds.size.width * anchorPoint.x, y: bounds.size.height * anchorPoint.y)
        var oldPoint = CGPoint(x: bounds.size.width * layer.anchorPoint.x, y: bounds.size.height * layer.anchorPoint.y)

        newPoint = newPoint.applying(transform)
        oldPoint = oldPoint.applying(transform)

        var position = layer.position
        position.x -= oldPoint.x
        position.x += newPoint.x

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

        layer.position = position
        layer.anchorPoint = anchorPoint
    }
}

将视图添加到情节提要并设置自定义类

现在为UIView设置新的锚点

启用“显示锚点”将显示一个红点，因此您可以更好地看到锚点在视觉上的位置。您以后随时可以将其关闭。

当计划在UIViews上进行转换时，这确实对我有所帮助。

对于Swift 3：

func setAnchorPoint(_ anchorPoint: CGPoint, forView view: UIView) {
    var newPoint = CGPoint(x: view.bounds.size.width * anchorPoint.x, y: view.bounds.size.height * anchorPoint.y)
    var oldPoint = CGPoint(x: view.bounds.size.width * view.layer.anchorPoint.x, y: view.bounds.size.height * view.layer.anchorPoint.y)

    newPoint = newPoint.applying(view.transform)
    oldPoint = oldPoint.applying(view.transform)

    var 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
}

扩展了Magnus的详尽解答，我创建了一个可用于子层的版本：

-(void)setAnchorPoint:(CGPoint)anchorPoint forLayer:(CALayer *)layer
{
    CGPoint newPoint = CGPointMake(layer.bounds.size.width * anchorPoint.x, layer.bounds.size.height * anchorPoint.y);
    CGPoint oldPoint = CGPointMake(layer.bounds.size.width * layer.anchorPoint.x, layer.bounds.size.height * layer.anchorPoint.y);
    CGPoint position = layer.position;
    position.x -= oldPoint.x;
    position.x += newPoint.x;
    position.y -= oldPoint.y;
    position.y += newPoint.y;
    layer.position = position;
    layer.anchorPoint = anchorPoint;
}