UITextField swift

var loginTxt : UITextField! = nil

override func viewDidLoad() {

super.viewDidLoad()

view.backgroundColor = .white()
view.addSubview(loginTxtFunc())
}

func loginTxtFunc() -> UITextField {

if (loginTxt == nil) {

loginTxt = UITextField(frame: CGRect(x: 10, y: 70, width: 200, height: 40))
loginTxt.backgroundColor = .red()
//loginTxt.rightViewMode = .always
//loginTxt.rightView = rightView()
}

return loginTxt
}

func rightView() -> UIView {

let rightBtn = UIButton(frame:CGRect(x: 0, y: 0, width: 40, height: 40))
rightBtn.backgroundColor = .yellow()
rightBtn.isSelected = true
rightBtn.addTarget(self, action: #selector(btnClick),
for:.touchUpInside)

rightBtn.setTitle("n", for: .normal)
rightBtn.setTitle("s", for: .selected)

rightBtn.setTitleColor(UIColor.green(), for: .normal)
rightBtn.setTitleColor(UIColor.blue(), for: .selected)

return rightBtn
}

func btnClick(btn:UIButton) -> Void {

btn.isSelected = !btn.isSelected
btn.backgroundColor = btn.isSelected ? .yellow() : .red()
}