[UIKit] 라디오버튼

IBOutlet var btnRadioS: [UIButton]!
var radioIndex: Int?

@IBAction func btnAction(_ btn: UIButton) {
    if radioIndex != nil {
        if !btn.isSelected {
            for index in btnRadioS.indices {
                btnRadioS[index].isSelected = false
            }
            btn.isSelected = true
            radioIndex = btnRadioS.firstIndex(of: btn)
        } else {
            btn.isSelected = false
            radioIndex = nil
        }
    } else {
        btn.isSelected = true
        radioIndex = btnRadioS.firstIndex(of: btn)
    }
}