昨天我們已經能把單一地點的天氣資訊顯示到手機App上面了，接著我們會利用UIButton讓我們可以選擇想要的地點及時段！
首先，我們先拉一個UIButton進storyboard裡並拉好@IBOutlet

接著我們要寫按下Button後的@IBAction，我們會利用UIPickerView來完成選擇地點和時間的功能！

我們先宣告常數及變數

並在ViewDidLoad裡設定UIPickerView的DataSource和Delegate

接著來寫選取地點時間UIPickerView的function

func locationView() {
        let alertView = UIAlertController(
            title: "選擇地點",
            message: "\n\n\n\n\n\n\n\n\n",
            preferredStyle: .alert
        )
        let cancelAction = UIAlertAction(
            title: "取消",
            style: .cancel,
            handler: nil
        )
        let okAction = UIAlertAction(
            title: "確認",
            style: .default,
            handler: {_ in
                self.loadAPI(locationName: self.selectLocation, time: self.selectTime)
                self.timeView()
            }
        )
        alertView.view.addSubview(locationPickerView)
        alertView.addAction(cancelAction)
        alertView.addAction(okAction)
        present(alertView, animated: true, completion: nil)
    }
    func timeView() {
        let alertView = UIAlertController(
            title: "選擇時間",
            message: "\n\n\n\n\n\n\n\n\n",
            preferredStyle: .alert
        )
        let cancelAction = UIAlertAction(
            title: "取消",
            style: .cancel,
            handler: nil
        )
        let okAction = UIAlertAction(
            title: "確認",
            style: .default,
            handler: {_ in self.loadAPI(locationName: self.selectLocation, time: self.selectTime)}
        )
        alertView.view.addSubview(timePickerView)
        alertView.addAction(cancelAction)
        alertView.addAction(okAction)
        present(alertView, animated: true, completion: nil)
    }

最後寫一個extension

extension ViewController: UIPickerViewDataSource, UIPickerViewDelegate {
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        if pickerView == locationPickerView {
            return location.count
        }
        if pickerView == timePickerView {
            return timeData.count
        }
        return 0
    }
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if pickerView == locationPickerView {
            return location[row]
        }
        if pickerView == timePickerView {
            return timeData[row]
        }
        return nil
    }
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if pickerView == locationPickerView {
            selectLocation = location[row]
        }
        if pickerView == timePickerView {
            selectTime = row
        }
    }
}

我們就能成功選擇地點和時間啦！