didSet willSet在init里面没有作用

今天修改了这个按钮类，用来在运行时根据数据来调整按钮的颜色和文字，修改后初始化的时候发现颜色和文字都没有设置，经研究和查证，在initializer内对变量进行初始化赋值是不会掉用didSet和willSet的～

class PopupButton : UIButton {
  
    let defaultHeight:CGFloat = 44
    let margin:CGFloat = 8
    let cornerRadius:CGFloat = 4
    
    var title:String! {
        didSet {
            if let t = title {
                self.updateTitle(title: t)
            }
        }
    }
    var index:Int = 0
    var type:PopupButtonType! {
        didSet {
            if let t = type {
                self.updateType(type: t)
            }
        }
    }
    
    // 在initializer中初始化变量是不会掉用didSet和willSet的
    init(title:String, buttonType:PopupButtonType = PopupButtonType.normal) {
        super.init(frame:CGRect(x: 0, y: 8, width: UIScreen.main.bounds.width - margin*2, height: defaultHeight))
        // didSet willSet 不会在init里面调用
        self.title = title        // 这里set后不会掉用didSet方法
        self.updateTitle(title: title)    // 这里必须调用updateTitle 
        self.type = buttonType    // 这里set后不会掉用didSet方法
        self.updateType(type: buttonType)  //这里必须调用updateType 
        self.alpha = 1
        self.layer.cornerRadius = cornerRadius
        self.layer.masksToBounds = true
        self.setBackgroundImage(AtColor.backgroundLight().getImage(), for: UIControlState.highlighted)
        self.setBackgroundImage(AtColor.white().getImage(), for: UIControlState())
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    fileprivate func updateTitle(title:String) {
        DispatchQueue.main.async {
            self.setTitle(self.title, for: UIControlState())
        }
    }
    
    fileprivate func updateType(type:PopupButtonType) {
        DispatchQueue.main.async {
            switch type {
            case PopupButtonType.normal:
                self.setTitleColor(atColor: AtColor.normalBlue(), forState: UIControlState())
            case PopupButtonType.warning:
                self.setTitleColor(atColor: AtColor.iconRed(), forState: UIControlState())
            case PopupButtonType.disabled:
                self.setTitleColor(atColor: AtColor.textLightGray(), forState: UIControlState())
            }
        }
    }
}