在后台运行的 iPhone 应用程序在 10 分钟后终止

Question

我正在开发一个需要在 iOS4 上后台运行的应用程序。一世 希望它像普通的基于位置的应用程序，所以 BackgroundMode 是 设置到位置。应用程序进入后台运行良好 状态，但 10 分钟后，它不再响应。也许它 被暂停/终止。 我想要做的是永远在后台运行应用程序 在用户终止应用程序之前没有任何时间限制 只。请指导我如何实现这一目标。 在这里，当 GPS 更新到新位置时，我会弹出本地通知。这里提供了一些代码片段：

- (void)applicationDidEnterBackground:(UIApplication *)application {
    /*
     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, called instead of applicationWillTerminate: when the user quits.
     */


 UIApplication*    app = [UIApplication sharedApplication];

    // Request permission to run in the background. Provide an
    // expiration handler in case the task runs long.
    NSAssert(bgTask == UIBackgroundTaskInvalid, nil);

    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
        // Synchronize the cleanup call on the main thread in case
        // the task actually finishes at around the same time.
        dispatch_async(dispatch_get_main_queue(), ^{

            if (bgTask != UIBackgroundTaskInvalid)
            {
                [app endBackgroundTask:bgTask];
                bgTask = UIBackgroundTaskInvalid;
            }
        });
    }];

    // Start the long-running task and return immediately.

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // Do the work associated with the task.

  locmanager = [[CLLocationManager alloc] init];
  [locmanager setDelegate:self];
  [locmanager setDesiredAccuracy:kCLLocationAccuracyBest];
  locmanager.distanceFilter = 20;
  [locmanager startUpdatingLocation];

  NSLog(@"App staus: applicationDidEnterBackground");
        // Synchronize the cleanup call on the main thread in case
        // the expiration handler is fired at the same time.
        dispatch_async(dispatch_get_main_queue(), ^{
            if (bgTask != UIBackgroundTaskInvalid)
            {
                [app endBackgroundTask:bgTask];
                bgTask = UIBackgroundTaskInvalid; 
            }
        });  
    });
 NSLog(@"backgroundTimeRemaining: %f", [[UIApplication sharedApplication] backgroundTimeRemaining]);
}

and

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{ 
 // Log the kind of accuracy we got from this
 NSLog(@"Accuracy-------- %f %f", [newLocation horizontalAccuracy], [newLocation verticalAccuracy]);

 CLLocationCoordinate2D loc = [newLocation coordinate];
 userCurrentLocation = newLocation;
 lat = loc.latitude;
 lon = loc.longitude;

 UILocalNotification *localNotif = [[UILocalNotification alloc] init];
    if (localNotif == nil)
        return;
 NSDate *now = [NSDate dateWithTimeIntervalSinceNow:10]; 

 NSLog(@"Now is %@",now); 

 localNotif.fireDate = now;

    localNotif.timeZone = [NSTimeZone defaultTimeZone];

 // Notification details
    localNotif.alertBody = [NSString stringWithFormat:@"Latitude = %f, Longitude = %f", lat, lon];
 // Set the action button
    localNotif.alertAction = @"View";

    localNotif.soundName = UILocalNotificationDefaultSoundName;
    localNotif.applicationIconBadgeNumber = 1;

 // Specify custom data for the notification
    NSDictionary *infoDict = [NSDictionary dictionaryWithObject:@"someValue" forKey:@"someKey"];
    localNotif.userInfo = infoDict;

 // Schedule the notification
    [[UIApplication sharedApplication] scheduleLocalNotification:localNotif];
    [localNotif release];

}

请指导我如何做到这一点？

Answer 1

您的 info.plist 包含这些内容？

应用程序可以将自己声明为连续的后台位置应用程序。需要标准位置服务提供的定期位置更新的应用程序可以将自己声明为连续后台应用程序。它通过在其 Info.plist 文件中包含 UIBackgroundModes 键并将此键的值设置为包含位置字符串的数组来实现此目的。如果具有此密钥的应用程序在进入后台时正在运行定位服务，则不会被系统挂起。相反，它被允许继续运行，以便它可以在后台执行与位置相关的任务。

http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html%23//apple_ref/doc/uid/TP40007072-CH5

Answer 2

您不需要执行 beginBackgroundTask...（实际上您不应该），通过注册位置更新（请参阅上面的帖子），您的应用程序将自动被唤醒并通知位置更改.后台任务用于其他目的（延长下载等），您只有有限的时间来执行它们（大约 10 分钟），如果您尝试将后台任务保持打开更长的时间，您的应用程序将被终止。

基本上摆脱了 beginBackgroundTask 的东西，并将 UIBackgroundModes -> location 键添加到您的 info.plist 中，以便您注册后即使在后台也可以让您的应用通知位置更改。