当我在明确选择一行之前选择 UIPickerView 上的“完成”按钮时，应用程序崩溃

Posted 2023-02-24

【中文标题】当我在明确选择一行之前选择 UIPickerView 上的“完成”按钮时，应用程序崩溃

【英文标题】：App crashes when I select "done" button on UIPickerView before explicitly selecting a row

【发布时间】：2020-03-08 22:56:46

【问题描述】：

除非我明确选择一行，否则 UIPickerView 会崩溃并出现错误

*** 由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“时间间隔必须大于 0”

我知道它崩溃是因为它没有选择任何行，时间间隔的默认值为 0。

那么我怎样才能让PickerView 选择第一行而无需我自己明确选择呢？

以下是相关代码：

var timerDisplayed = 0


func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
            timerDisplayed = Int(timeSelect[row])!

        

 @objc func timeClock()

        UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound])  (didAllow, error) in 
        let content = UNMutableNotificationContent()
        content.title = "Time is up!"
        content.badge = 1
        content.sound = UNNotificationSound.init(named: UNNotificationSoundName(rawValue: "note1.wav"))

        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: TimeInterval(timerDisplayed), repeats: false)

        let request = UNNotificationRequest(identifier: "timerDone", content: content, trigger: trigger)
        UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)


        self.timerTextField.text = ("  \(String(self.timerDisplayed))")
        dismissKeyboard()
        DispatchQueue.main.async 
            self.timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.Action), userInfo: nil, repeats: true)
        
    

    @objc func Action()
        if timerDisplayed != 0 
            DispatchQueue.main.async 
                self.timerDisplayed -= 1
                self.timerTextField.text = ("  \(String(self.timerDisplayed))")
            
        
        else 
            self.timer.invalidate()
            self.timerTextField.text = nil
            self.timerTextField.placeholder = "   Timer"
        
    

【参考方案1】：

也许你可以使用你的 timeClock() 方法，在第一行有这个：

let timerDisplayed = self.timerDisplayed > 0 ? timerDisplayed : Int(timeSelect[0])!

所以它可能看起来像这样：

@objc func timeClock()
    let timerDisplayed = self.timerDisplayed > 0 ? timerDisplayed : Int(timeSelect[0])!
    UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound])  (didAllow, error) in 
    let content = UNMutableNotificationContent()
    content.title = "Time is up!"
    content.badge = 1
    content.sound = UNNotificationSound.init(named: UNNotificationSoundName(rawValue: "note1.wav"))

    let trigger = UNTimeIntervalNotificationTrigger(timeInterval: TimeInterval(timerDisplayed), repeats: false)

    let request = UNNotificationRequest(identifier: "timerDone", content: content, trigger: trigger)
    UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)

    self.timerTextField.text = ("  \(String(self.timerDisplayed))")
    dismissKeyboard()
    DispatchQueue.main.async 
        self.timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.Action), userInfo: nil, repeats: true)
    

或者您可以将其放入 viewDidLoad 以自动选择第一行：

let defaultFirstRow = pickerView.selectedRow(inComponent: 0);
pickerView(pickerView, didSelectRow: defaultFirstRow, inComponent:0)

【讨论】：

我编辑了答案以显示一个工作示例，以在 viewdidload 中自动选择第一行作为默认值，或者通过使用 timerDisplayed 变量来调整您的代码以按照您希望的方式工作。请看一下：D

是的，做到了！谢谢！