OnClick example for single choice RadioButton group

SingleChoiceOnClick.swift

func onClick(_ sender: UIView) {
  guard let currentRadioButton = sender as? RadioButton else {
    return
  }

  [
    radioButton1,
    radioButton2
  ].forEach { $0.isChecked = false } // Set all to unchecked first
  currentRadioButton.isChecked = !currentRadioButton.isChecked
}