// 1. 新建 MyView.xib 文件
// 2. 新建 MyView 类
// 3. 增加如下代码
class MyView: UIView {

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.commomInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.commomInit()
    }

    // TODO: 将Xib的FileOwner设置该View
    func commomInit() {
        let view = Bundle.main.loadNibNamed("MyView", owner: self, options: nil)?.first as! UIView
        self.addSubview(view)
        view.frame = self.bounds
    }
}
// 4. 将 MyView.xib的FileOwner设置为MyView

// 使用
let v = MyView(frame: CGRect(x: 0, y: 0, width: ScreenWidth, height: 50))