我相信子视图的高度和宽度仍然是0，因为按钮没有绑定到任何边缘，按钮似乎定义了它的超级视图的高度。你可以通过设置clipToBounds = true来检查。如果在视图中使用self，调用lazy总是好的。
这可以解决你的问题：

class buttonView: UIView {
private lazy var button: UIButton = {
    let button = UIButton()
    button.setTitleColor(.gray, for: .normal)
    button.setTitle("MyButton", for: .normal)
    button.translatesAutoresizingMaskIntoConstraints = false
    button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
    return button
}()
override init(frame: CGRect) {
    super.init(frame: frame)
    setup()
}
required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    setup()
}
func setup() {
    addSubview(button)
    
    addConstraint(NSLayoutConstraint(item: button, attribute: .top, relatedBy: .equal, toItem: self, attribute: .top, multiplier: 1, constant: 10))
    addConstraint(NSLayoutConstraint(item: button, attribute: .leading, relatedBy: .equal, toItem: self, attribute: .leading, multiplier: 1, constant: 10))
    addConstraint(NSLayoutConstraint(item: button, attribute: .bottom, relatedBy: .equal, toItem: self, attribute: .bottom, multiplier: 1, constant: 0))
    addConstraint(NSLayoutConstraint(item: button, attribute: .trailing, relatedBy: .equal, toItem: self, attribute: .trailing, multiplier: 1, constant: 0))
    addConstraint(NSLayoutConstraint(item: button, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 80))
    addConstraint(NSLayoutConstraint(item: button, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 35))
}
@objc func buttonAction() {
    //Do stuff
    }
}

对NSLayoutConstraints有点不确定，因为我使用SnapKit或锚点。但我认为这应该是正确的。

我也有同样的问题。要解决这个问题，只需将isUserInteractionEnabled = true设置为PANView（添加按钮子视图的视图）

在Masterbed属性里面，输入userinteractionenbaled = true，这将解决问题，其他的东西是addSubview.把它放在子视图项或类上..比如masterBed.addSubView（youurButton），如果你在按钮上使用用户交互，真的没有意义，因为按钮已经是一个为交互创建的对象。这是同样的事情，如果我们把一个按钮放在UIImageView上，我们需要在UIImageView上的属性上激活，以与按钮交互。就像这个样品一样。

class ViewController: UIViewController {
 let myImage: UIImageView = {
    let image = UIImageView()
    image.backgroundColor = UIColor.brown
    image.translatesAutoresizingMaskIntoConstraints = false
    image.isUserInteractionEnabled = true    // here activate the interaction needed
    image.image = UIImage(imageLiteralResourceName: "backgroundSE.jpg")
    return image
}()
let textLabel: UILabel = {
   let label = UILabel()
    label.text = "My App"
    label.textColor = UIColor.white
    label.font = UIFont.boldSystemFont(ofSize: 25)
    label.textAlignment = .center
    label.translatesAutoresizingMaskIntoConstraints = false
    return label
}()
lazy var sendMailButton: UIButton = {
    let button = UIButton(type: .system)
    button.setTitle("Send Mail", for: .normal)
    button.setTitleColor(.white, for: .normal)
    button.backgroundColor = UIColor(white: 0.5, alpha: 0.5)
    button.translatesAutoresizingMaskIntoConstraints = false
    button.layer.cornerRadius = 14
    button.addTarget(self, action: #selector(handleSendMail), for: .touchUpInside)
    return button
}()
override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(myImage)
    myImage.addSubview(sendMailButton)
    myImage.addSubview(textLabel)
    setupLayouts()
}
@objc func handleSendMail() {
    print("Mail Sended")
}

我希望这对你有帮助，解决这个问题，干杯！

可能是你的子视图是出了父视图框架，所以你可以尝试给予相同的框架作为父视图框架，并尝试这样做：

let button = UIButton(frame: self.frame)//Parent view frame
button.setTitleColor(.gray, for: .normal)
//button.center = CGPoint(x: 380, y: 110) // comment this line 
button.setTitle(">", for: .normal)
button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
self.addSubview(button)

我已经编辑了你的代码如下，它的工作。

您的ViewController类

class ViewController: UIViewController, HomeViewDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        middleView()
    }
    func middleView() {
        let customView = HomeView(frame: CGRect(x: 60, y: 100, width: 250, height: 100))
        self.view.addSubview(customView)
        customView.backgroundColor = UIColor.green
        customView.delegate = self
    }
    func buttonAclicked(_ sender: UIButton) {
        print("button click action in viewController")
    }
}

HomeView类

import UIKit
protocol HomeViewDelegate {
    func buttonAclicked(_ sender: UIButton)
}
class HomeView: UIView {
    var delegate:HomeViewDelegate?
    override init(frame: CGRect) {
        super.init(frame: frame)
        initView()
    }
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    func initView() {
        let button = UIButton(frame: CGRect(x: 10, y: 10, width: 80, height: 35))
        self.addSubview(button)
        button.setTitleColor(.gray, for: .normal)
        button.setTitle("MyButton", for: .normal)
        button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
    }
    func buttonAction(_ sender: UIButton) {
        print("button pressed")
        delegate?.buttonAclicked(sender)
    }
}