如何初始化自定义UIView并添加子视图？

class CustomView: UIView {
    // 自定义视图的代码
}

class CustomView: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        // 初始化代码
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        // 初始化代码
    }
    
    // 自定义视图的代码
}

class CustomView: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupSubviews()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupSubviews()
    }
    
    private func setupSubviews() {
        // 添加子视图的代码
        let subview = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        subview.backgroundColor = UIColor.red
        addSubview(subview)
    }
    
    // 自定义视图的代码
}

let customView = CustomView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
parentView.addSubview(customView)