CGPointApplyAffineTransform 中锚点的位置不正确 (iOS/Swift)

Question

看来我的buttonView的anchor point是根据view的位置变化的。我希望 buttonView 收缩到自身的中间而不是 view 的中间。我想知道我做错了什么？或者如果我完全误解了锚点？我试着阅读了一些文章，但它们似乎暗示一个对象的锚点是指它自己的坐标而不是它的父视图的坐标。

import UIKit

class ViewController: UIViewController {
    var buttonView:UIView!
    var toggleButton:UIButton!
    var isVisible = false

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let buttonTitles = ["1", "2", "3"]
        let size:CGFloat = 100.0

        let viewSize = CGFloat(buttonTitles.count) * size
        buttonView = UIView(frame: CGRectMake(40, 40, viewSize, viewSize))

        setAnchorPoint(CGPointMake(0.5, 0), forView: buttonView)
        buttonView.layer.anchorPoint = CGPointMake(0.5, 0.0)
        view.addSubview(buttonView)

        for (index, title) in buttonTitles.enumerate() {
            let button = UIButton(type: .Custom) as UIButton
            button.frame = CGRectMake(0, size * CGFloat(index), size, size)
            button.setTitle(title, forState: .Normal)
            button.backgroundColor = UIColor.redColor()
            buttonView.addSubview(button)
        }

        toggleButton = UIButton(type: .Custom) as UIButton
        toggleButton.frame = CGRectMake(200, 100, 80, 50)
        toggleButton.setTitle("Toggle", forState: .Normal)
        toggleButton.backgroundColor = UIColor.purpleColor()
        toggleButton.addTarget(self, action: #selector(ViewController.animate), forControlEvents: .TouchUpInside)
        view.addSubview(toggleButton)
    }

    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
    }

    func animate() {

        if (isVisible) { // collapse it
            isVisible = false

            UIView.animateWithDuration(0.5, animations: { 
                self.buttonView.transform = CGAffineTransformMakeScale(0.2, 0.2)
            })
        }

        else { // expand it
            isVisible = true

            UIView.animateWithDuration(0.5, animations: {
                self.buttonView.transform = CGAffineTransformMakeScale(1.0, 1.0)
            })
        }
    }   
}

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Answer 1

没关系，我只是把 buttonView's 宽度设置得太大了。

CGPointApplyAffineTransform 中锚点的位置不正确 (iOS/Swift)

Incorrect position of anchor point in CGPointApplyAffineTransform (iOS/Swift)

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