textField.keyboardType = UIKeyboardType.emailAddress
textField.becomeFirstResponder()
textField.placeholder = "이메일 입력"
순서대로 코드는 아래와 같다!
textField.borderStyle = UITextField.BorderStyle.roundedRect // 기본 스타일
textField.borderStyle = UITextField.BorderStyle.bezel
textField.borderStyle = UITextField.BorderStyle.line
textField.clearButtonMode = .always
textField.returnKeyType = .next