CGPointApplyAffineTransform 中的锚点位置不正确（iOS/Swift）

Question

我的buttonView 的anchor point 似乎是根据view 的位置而变化的。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？我尝试阅读一些文章，但它们似乎暗示一个对象的锚点指的是它自己的坐标而不是它的超级视图。

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，原来我只是将buttonView's 的宽度设置得太大了。