Swift3.0 UITextField

import UIKit

private var textfieldd = UITextField()
class TextFieldViewController: UIViewController,UITextFieldDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        
        //設置大小
        textfieldd.frame = CGRect(x: 0, y: 100, width: 300, height: 50)
        
         // 設置 樣式 (.none 無邊框  .line 直線邊框  .roundedRect 圓角矩形邊框  .bezel 邊線+陰影)
        textfieldd.borderStyle = .roundedRect
        
        //提示字
        textfieldd.placeholder = "提示字"
        textfieldd.textColor = UIColor.blue
        textfieldd.font = UIFont.boldSystemFont(ofSize: 20)
        textfieldd.textAlignment = .right
       
        // 設置 文字超出文本框時自適應大小
        textfieldd.adjustsFontSizeToFitWidth = true
        // 設置 最小可縮小的字號
        textfieldd.minimumFontSize = 14
        
        //清理按鈕
        textfieldd.clearButtonMode = .whileEditing
        
        //鍵盤樣式
        textfieldd.keyboardType = .default
        
        textfieldd.delegate = self
        
        
        
        self.view.addSubview(textfieldd)
        
    }
    
    
    ////////////////////////////////代理方法////////////////////////////////////
    // 輸入框詢問是否能夠編輯 true 能夠編輯  false 不能編輯
    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
        print("我要開始編輯了...")
        return true
    }
    // 該方法表明輸入框已經能夠開始編輯  進入編輯狀態
    func textFieldDidBeginEditing(_ textField: UITextField) {
        print("我正在編輯狀態中...")
    }
    // 輸入框將要將要結束編輯
    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
        print("我即將編輯結束...")
        return true
    }
    // 輸入框結束編輯狀態
    func textFieldDidEndEditing(_ textField: UITextField) {
        print("我已經結束編輯狀態...")
    } // 文本框是否能夠清除內容
    func textFieldShouldClear(_ textField: UITextField) -> Bool {
        return true
    }
    // 輸入框按下鍵盤 return 收回鍵盤
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }
    // 該方法當文本框內容出現變化時 及時獲取文本最新內容
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        
        return true
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}