pickerview 問題：當快速滑動滾輪時畫面選取的 row 和偵測選擇的 row 不同

當畫面選取和偵測選取不一致可能會導致寫程式時邏輯錯誤，也會讓使用者困惑。

碰到的問題

發現如果快速滑動滾輪後，畫面灰色底所選取的列可能會和偵測滾輪選取的列不同。(範例是透過下方文字顯示偵測滾輪選取的列)

滾輪設置

func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 3
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        if component == 0 {
            return 24
        } else {
            return 60
        }
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if component == 0 {
            return row.description
        } else {
            return row.description
        }
}

文字顯示選取的列

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if component == 0 {
            hour = row.description
        } else if component == 1 {
            min = row.description
        } else if component == 2 {
            sec = row.description
        }
        // 選擇的時間以字串顯示
        timeToString()
}
func timeToString(){
        // 選擇的時間以字串顯示
        formatter.dateFormat = "HH:mm:ss"
        guard let time = formatter.date(from: "\(hour):\(min):\(sec)") else { return }
        let timeToString = formatter.string(from: time)
        timeLabel.text = "\(timeToString)\n\n第一列：\(timePickerview.selectedRow(inComponent: 0))\n第二列：\(timePickerview.selectedRow(inComponent: 1))\n第三列：\(timePickerview.selectedRow(inComponent: 2))"
        
}

目前解決方式

滾輪滑動後，將畫面移動到偵測選取的 row ，避免兩者不一致。

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if component == 0 {
            hour = row.description
        } else if component == 1 {
            min = row.description
        } else if component == 2 {
            sec = row.description
        }
        // 將畫面移動至偵測選取的row
        timePickerview.selectRow(row, inComponent: component, animat  ed: false)
        // 選擇的時間以字串顯示
        timeToString()
}