swift5.0 UITextfield

//1.创建

lettextfield =UITextField(frame:CGRect(x:50,y:100,width:200,height:40))

textfield.borderStyle= .none

self.view.addSubview(textfield)

//2.设置placeHolder

textfield.placeholder="请输入密码"

//3.文字超过文本框长度,自动缩小字体,且设置最小字体

textfield.adjustsFontSizeToFitWidth=true

textfield.minimumFontSize=14

//4.对齐方式

textfield.textAlignment= .center

//5.设置背景图片

textfield.borderStyle= .none

textfield.background=UIImage(named:"backImg")

//6.右侧的 X 关闭按钮

textfield.clearButtonMode= .always

//7.设置键盘类型

textfield.keyboardType= .numberPad

//8.第一响应者

textfield.becomeFirstResponder()

textfield.resignFirstResponder()

//9.设置代理

textfield.delegate=self;

//10.绑定事件

textfield.addTarget(self, action:#selector(textfieldAction), for: .editingChanged)