当iPhone应用程序在后台运行时显示弹出窗口(UIAlertView

Question

我是iphone应用程序开发的新手。

我的问题是，当我的应用程序在后台运行时，我如何显示弹出窗口(UIAlertView)？我正在使用iOS6的xcode 4.2，我无法在互联网上找到满意的答案。有没有人能帮我一下？

    - (void)applicationDidEnterBackground:(UIApplication *)application
      {
         UIApplication* app = [UIApplication sharedApplication];
         bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
            [app endBackgroundTask:bgTask];
            bgTask = UIBackgroundTaskInvalid;
         }];

         dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
         NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(doBackgroundProcessing) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
        [[NSRunLoop currentRunLoop] run];
    });

}

    - (void) doBackgroundProcessing
    {
        global = [lMGlobal getInstance];

        while(TRUE)
        {
            [self showAlertFor:@"Hello" andMessage:@"Wake up"];

            [NSThread sleepUntilDate:[lMGlobal getSleepDuration]];

        }

    }

    - (void) showAlertFor:(NSString *)title andMessage:(NSString*)message
      {
          UIAlertView *alertDialog;
          alertDialog = [[UIAlertView alloc]
               initWithTitle:title
               message:message
               delegate: self
               cancelButtonTitle: nil
               otherButtonTitles: @"Mute", nil];

          [alertDialog
          performSelector:@selector(show)
          onThread:[NSThread mainThread]
          withObject:nil
          waitUntilDone:NO];
          [alertDialog release];
      }

Answer 1

虽然不能显示UIAlertView，但可以显示UILocalNotification。您的代码可能如下所示：

backupAlarm = [[UILocalNotification alloc] init];

backupAlarm.fireDate = alarmTime;
backupAlarm.timeZone = [NSTimeZone systemTimeZone];

backupAlarm.alertBody = @"Good morning, time to wake up.";
backupAlarm.alertAction = @"Show me";
backupAlarm.soundName = UILocalNotificationDefaultSoundName;

Answer 2

不可能让你的应用程序在后台运行时显示UIAlertView。

Answer 3

我认为你不能直接这么做，但你可以 UILocalNotification!