Trouble aligning a UIView and a CAShapeLayer

问题:

I'm having trouble aligning a UIView and a CAShapeLayer.

Here is sample code demonstrating the issue:

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let square = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
        square.transform = CGAffineTransformMakeRotation(CGFloat(20*M_PI/180))
        square.backgroundColor = UIColor.grayColor()
        view.addSubview(square)

        let strokeLayer = CAShapeLayer()
        strokeLayer.path = UIBezierPath(rect: square.bounds).CGPath
        strokeLayer.position = square.center
        strokeLayer.setAffineTransform(square.transform)

        strokeLayer.fillColor = UIColor.clearColor().CGColor
        strokeLayer.strokeColor = UIColor.redColor().CGColor
        strokeLayer.lineWidth = 1

        view.addSubview(square)
        view.layer.addSublayer(strokeLayer)
    }
}

Here's an image of the result:

How do I get the two to align?

回答1:

The only change you would need to make is to add:

strokeLayer.frame = square.layer.bounds

Right after:

let strokeLayer = CAShapeLayer()

I.e.,

let strokeLayer = CAShapeLayer()
strokeLayer.frame = square.layer.bounds
strokeLayer.path = UIBezierPath(rect: square.bounds).CGPath
strokeLayer.position = square.center
strokeLayer.setAffineTransform(square.transform)

strokeLayer.fillColor = UIColor.clearColor().CGColor
strokeLayer.strokeColor = UIColor.redColor().CGColor
strokeLayer.lineWidth = 1

回答2:

What if you position your shape layer at (0,0)

strokeLayer.position = CGPointMake( 0, 0 )