swift 點擊Textfield 后自動上移,避免鍵盤被遮住

一些textfield在鍵盤顯示出來的時候會被擋住，所以在編輯textfield我們可以把視圖上移

方法是給textfield增加兩個監聽事件

    @IBAction func beginEdit(_ sender: UITextField) {
        animateViewMoving(up: true, moveValue: 100)
    }
        
    @IBAction func endEdit(_ sender: UITextField) {
        animateViewMoving(up: false, moveValue: 100)
    }
    
    func animateViewMoving (up:Bool, moveValue :CGFloat){
        let movementDuration:TimeInterval = 0.3
        let movement:CGFloat = ( up ? -moveValue : moveValue)
        UIView.beginAnimations( "animateView", context: nil)
        UIView.setAnimationBeginsFromCurrentState(true)
        UIView.setAnimationDuration(movementDuration )
        self.view.frame = self.view.frame.offsetBy(dx: 0,  dy: movement)
        UIView.commitAnimations()
    }