在Swift中的现有图层下方插入子图层时出现问题？

Question

我正在尝试在Swift中的现有层后面添加一个子层，但是该子层仍然位于现有层的前面-我的代码中肯定有问题；

import UIKit

class ViewController: UIViewController {

let mainView = UIView()
let screenWidth = UIScreen.main.bounds.width
let screenHeight = UIScreen.main.bounds.height
let focusBG = UIView()

override func viewDidLoad() {
    super.viewDidLoad()

    mainView.backgroundColor = UIColor.gray
    view.addSubview(mainView)
    mainView.translatesAutoresizingMaskIntoConstraints = false
    mainView.widthAnchor.constraint(equalToConstant: 325).isActive = true
    mainView.heightAnchor.constraint(equalToConstant: ((325 / 9) * 16)).isActive = true
    mainView.topAnchor.constraint(equalTo: view.topAnchor, constant: 100).isActive = true
    mainView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true

    let tapView = UIView(frame: CGRect(x: 50, y: 0, width: 150, height: 200))
    tapView.backgroundColor = UIColor.red
    mainView.addSubview(tapView)

    focusBG.frame = CGRect(x: 0, y: 0, width: screenWidth, height: screenHeight)
    focusBG.backgroundColor = UIColor(hue: 0.0, saturation: 0.0, brightness: 0.0, alpha: 0.4)
    self.view.layer.insertSublayer(focusBG.layer, below: tapView.layer)
}

}

理想情况下，红色框应位于灰色层的前面-但这就是我得到的；

谢谢！

更新：工作代码

        self.mainView.insertSubview(focusBG, belowSubview: tapView)

    focusBG.translatesAutoresizingMaskIntoConstraints = false
    focusBG.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
    focusBG.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    focusBG.widthAnchor.constraint(equalToConstant: screenWidth).isActive = true
    focusBG.heightAnchor.constraint(equalToConstant: screenHeight).isActive = true

Answer 1

您可以尝试

self.mainView.insertSubview(focusBG, belowSubiew: tapView)

或

self.mainView.layer.insertSublayer(focusBG.layer, below: tapView.layer) // not tested 

Answer 2

尝试使用insertSublayer，该方法对我有效。

self.mainView.layer.insertSublayer(your_Layer, at: 1) // 1 is the position of the layer you want to add to the mainView.

谢谢，让我知道这是否适合您。如果这样做，不要忘记投票；）