1.Textfiled的创建

let textField:UITextField =  UITextField(frame: CGRect(x: 20, y: 100, width: 240, height: 40))
self.view.addSubview(textField)

2.Textfiled的基础应用

//设置输入框风格为line
textField.borderStyle = UITextField.BorderStyle.line
//设置输入框风格为bezel
textField.borderStyle = UITextField.BorderStyle.bezel
//设置输入框的提示文字
textField.placeholder = "请输入文字"
//设置输入的文字颜色
textField.textColor = UIColor.blue
//设置文字的字体
textField.font = UIFont.italicSystemFont(ofSize: 20)
//设置文字的对齐方式
textField.textAlignment = NSTextAlignment.center
//textField.backgroundColor = UIColor.red
//是否每次进入编辑状态时都清空输入框中的文字
textField.clearsOnBeginEditing =  true
//是否字体大小自适应
textField.adjustsFontSizeToFitWidth = true
//设置输入框为无效
//textField.isEnabled = false
//设置输入框的左视图
let viewLeft:UIView =  UIView(frame: CGRect(x: 0, y: 0, width: 40, height: 40))
let viewRight: UIView = UIView(frame: CGRect(x: 0, y: 0, width: 40, height: 40))
viewLeft.backgroundColor = UIColor.red
viewRight.backgroundColor = UIColor.blue
textField.leftView = viewLeft
textField.rightView = viewRight
//设置左右视图的显示模式
textField.leftViewMode = UITextField.ViewMode.always
textField.rightViewMode = UITextField.ViewMode.always
//设置弹出的交互键盘
let board:UIView = UIView(frame: CGRect(x: 0, y: 0, width: 320, height: 50))
board.backgroundColor = UIColor.orange
//textField.inputView = board
//设置副键盘视图
textField.inputAccessoryView = board
//设置代理
textField.delegate = self
//设置文本框删除按钮的显示模式
textField.clearButtonMode = UITextField.ViewMode.always

3.Textfiled的方法函数

//当输入改变时调用的方法
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    print(string)
    return true
}
//textField已经进入编辑状态时调用的方法
func textFieldDidBeginEditing(_ textField: UITextField) {
    print("didBegin")
}
//结束编辑状态时调用的方法
func textFieldDidEndEditing(_ textField: UITextField) {
    print("didEnd")
}
//将要进入编辑状态时调用的方法
func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
    print("shouldBegin")
    return true
}
//将要结束编辑状态时调用的方法
func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
    print("shouldEnd")
    return true
}
//当点击删除按钮时触发的方法
func textFieldShouldClear(_ textField: UITextField) -> Bool {
    return false
}
//点击return键触发的方法
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return true
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    textField.resignFirstResponder()
    }