问自定义绘图UIView在iOS 9上崩溃，但在其他系统上可以正常工作

EN

import UIKit

class CustomView: UIView {
    private let customLayer: CustomLayer = CustomLayer()

    init(color: UIColor) {
        super.init(frame: .zero)
        self.customLayer.color = color
    }

    required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") }

    override func didMoveToWindow() {
       super.didMoveToWindow()
       setupAnimation()
    }

    private func setupAnimation() {
       ...
   }
}

fileprivate class CustomLayer: CALayer {
    var color: UIColor = .white

    override init() { super.init() }
    override init(layer: Any) { super.init(layer: layer)  }
    required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") }
    override func draw(in ctx: CGContext) { 
    // Some CoreGraphics drawing commands
    }


}