protocol SwitchKeyboardDelegate: class {
    func switchKeyboard()
}

class CustomAccessoryView: UIView {

    weak var delegate: SwitchKeyboardDelegate!

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

    override init(frame: CGRect) {
        super.init(frame: frame)
        initializeSubviews()
    }

    func initializeSubviews() {
        // 不需包括xib檔名
        let xibFileName = "CustomAccessoryView"
        let view = Bundle.main.loadNibNamed(xibFileName, owner: self, options: nil)![0] as! UIView
        self.addSubview(view)
        view.frame = self.bounds
    }

    @IBAction func switchBtnTap(){
        self.delegate.switchKeyboard();
    }
}