ios – 10分钟后重置Swift应用程序

概述我正在使用 Swift制作小费计算器应用程序.我的目标是在10分钟后重置我的应用程序(换句话说,将我的所有标签设置为0.00美元并在NSUserDefaults中设置默认值). 我将这3个函数放在我的ViewController.swift文件中： func compareTimes(opens: NSDate?, closes: NSDate?) { if(opens!.timeInte 我正在使用 Swift制作小费计算器应用程序.我的目标是在10分钟后重置我的应用程序(换句话说,将我的所有标签设置为0.00美元并在NSUserDefaults中设置默认值).

我将这3个函数放在我的VIEwController.swift文件中：

func compareTimes(opens: NSDate?,closes: NSDate?) {    if(opens!.timeIntervalSinceReferenceDate-closes!.timeIntervalSinceReferenceDate>600) {        reset()    }}func openApp() {    openingTime = NSDate()    let defaults = NSUserDefaults.standardUserDefaults()    closingTime = defaults.objectForKey(closeKey) as! NSDate?    if (closingTime != nil) {        compareTimes(openingTime,closes: closingTime)    }}func closeApp() {    closingTime = NSDate()    let defaults = NSUserDefaults.standardUserDefaults()    defaults.setobject(closingTime,forKey: closeKey)}

在我的AppDelegate中,我调用了以下两种方法：

func applicationDIDEnterBackground(application: UIApplication) {    // Use this method to release shared resources,save user data,invalIDate timers,and store enough application state information to restore your application to its current state in case it is terminated later.    // If your application supports background execution,this method is called instead of applicationWillTerminate: when the user quits.    VIEwController().closeApp()}func applicationWillEnterForeground(application: UIApplication) {    // Called as part of the Transition from the background to the active state; here you can undo many of the changes made on entering the background.    VIEwController().openApp()}

请注意,当应用关闭时,会记录时间,当应用程序打开时,也会记录时间.比较这些时间,如果通过10分钟,则调用reset().

我的问题是当reset()被调用时,表示UILabels和UITextFIElds的所有变量都变为nil并且出现错误

Fatal error: unexpectedly found nil while unwrapPing an Optional value.

这是我的reset()方法供参考：

func reset() {    billFIEld.text=""    tipLabel.text = "+ "+formatter.stringFromNumber(0)!    totalLabel.text = formatter.stringFromNumber(0)    total2.text = formatter.stringFromNumber(0)    total3.text = formatter.stringFromNumber(0)    total4.text = formatter.stringFromNumber(0)    let defaults = NSUserDefaults.standardUserDefaults()    defaults.setobject("15",forKey: key1)    defaults.setobject("18",forKey: key2)    defaults.setobject("20",forKey: key3)    defaults.synchronize()    percentages.append(0.1)    percentages.append(0.1)    percentages.append(0.1)    percentbutton.setTitle("15%",forSegmentAtIndex: 0)    percentbutton.setTitle("18%",forSegmentAtIndex: 1)    percentbutton.setTitle("20%",forSegmentAtIndex: 2)}

解决方法 您的问题是当您说VIEwController().closeApp()时,您正在分配VIEwController的新实例并在该实例上调用closeApp函数.由于您没有从故事板中实例化该实例,因此没有附加任何插件,您将获得零引用异常.

您需要在现有VIEwController实例上调用方法.你可以使用这样的东西：

func applicationDIDEnterBackground(application: UIApplication) {    // Use this method to release shared resources,this method is called instead of applicationWillTerminate: when the user quits.    if let vIEwController = application.keyWindow?.rootVIEwController as? VIEwController {        vIEwController.closeApp()    }}func applicationWillEnterForeground(application: UIApplication) {    // Called as part of the Transition from the background to the inactive state; here you can undo many of the changes made on entering the background.    if let vIEwController = application.keyWindow?.rootVIEwController as? VIEwController {        vIEwController.closeApp()    }}

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