我们可以在位置更改时在后台重新启动应用程序吗？强制从后台退出后答案

【问题标题】：Can we Relaunch the application in the background on location change? after force quit it from background我们可以在位置更改时在后台重新启动应用程序吗？强制从后台退出后
【发布时间】：2013-07-08 00:38:49
【问题描述】：

我的要求是，如果我的应用程序从后台模式终止，之后如果发生任何重大的位置更改，它应该以后台模式启动。这正是startMonitoringSignificantLocationChanges的文件中所说的

如果您启动此服务并且您的应用程序随后终止，系统自动重新启动应用程序到新事件到达时的背景。在这种情况下，选项传递给应用程序的字典：didFinishLaunchingWithOptions：您的应用程序委托的方法包含密钥 UIApplicationLaunchOptionsLocationKey 来表明你的由于位置事件而启动了应用程序。重启后，您仍然必须配置一个位置管理器对象并调用它方法继续接收位置事件。当你重新启动位置服务，当前事件被传递给您的代表立即地。此外，您所在位置的 location 属性 manager 对象甚至填充了最新的位置对象在您开始定位服务之前。

所以我把这段代码

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

 if ([CLLocationManager significantLocationChangeMonitoringAvailable]) {
        // Stop normal location updates and start significant location change updates for battery efficiency.
        [viewController.locationManager stopUpdatingLocation];
        [viewController.locationManager startMonitoringSignificantLocationChanges];

        //NSLog(@"significantLocationChangeMonitoringAvailable.");
    }
    else {
        //NSLog(@"Significant location change monitoring is not available.");
    }
}

之后它也不会在后台模式下重新启动，尽管我在到处漫游后尝试更改我的位置。

我在这里遗漏或误导了什么？该应用程序没有在后台重新启动

有什么建议吗？

2013 年 7 月 12 日编辑

经过多次试验，我发现应用程序在后台重新启动后立即崩溃并显示崩溃日志

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0:
0   libsystem_kernel.dylib          0x3ba3feb4 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x3ba40048 mach_msg + 36
2   CoreFoundation                  0x337ff040 __CFRunLoopServiceMachPort + 124
3   CoreFoundation                  0x337fdd9e __CFRunLoopRun + 878
4   CoreFoundation                  0x33770eb8 CFRunLoopRunSpecific + 352
5   CoreFoundation                  0x33770d44 CFRunLoopRunInMode + 100
6   Foundation                      0x34093f92 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 250
7  AppNm                        0x0010a6a4 0xe4000 + 157348
8   AppNm                       0x000efc2a 0xe4000 + 48170
9   AppNm                       0x000e9796 0xe4000 + 22422
10  CoreLocation                    0x33cd1064 -[CLLocationManager onClientEventLocation:] + 2244
11  CoreLocation                    0x33cc8eaa __CLClientInvokeCallback_block_invoke_0 + 62
12  CoreFoundation                  0x337ff6ae __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 10
13  CoreFoundation                  0x337fed80 __CFRunLoopDoBlocks + 156
14  CoreFoundation                  0x337fdca8 __CFRunLoopRun + 632
15  CoreFoundation                  0x33770eb8 CFRunLoopRunSpecific + 352
16  CoreFoundation                  0x33770d44 CFRunLoopRunInMode + 100
17  GraphicsServices                0x373492e6 GSEventRunModal + 70
18  UIKit                           0x356862fc UIApplicationMain + 1116
19  AppNm                       0x000e5854 0xe4000 + 6228
20  AppNm                       0x000e57a4 0xe4000 + 6052

Thread 1 name:  Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0   libsystem_kernel.dylib          0x3ba40648 kevent64 + 24
1   libdispatch.dylib               0x3b970974 _dispatch_mgr_invoke + 792
2   libdispatch.dylib               0x3b970654 _dispatch_mgr_thread$VARIANT$mp + 32

Thread 2:
0   libsystem_kernel.dylib          0x3ba50d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x3b99ecf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x3b99ea12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x3b99e8a0 start_wqthread + 4

Thread 3 name:  WebThread
Thread 3:
0   libsystem_kernel.dylib          0x3ba500fc __psynch_mutexwait + 24
1   libsystem_c.dylib               0x3b999124 pthread_mutex_lock + 388
2   WebCore                         0x39786418 _WebTryThreadLock(bool) + 184
3   WebCore                         0x3978634a WebRunLoopLock(__CFRunLoopObserver*, unsigned long, void*) + 42
4   CoreFoundation                  0x337ff6ca __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 18
5   CoreFoundation                  0x337fd9bc __CFRunLoopDoObservers + 272
6   CoreFoundation                  0x337fdde8 __CFRunLoopRun + 952
7   CoreFoundation                  0x33770eb8 CFRunLoopRunSpecific + 352
8   CoreFoundation                  0x33770d44 CFRunLoopRunInMode + 100
9   WebCore                         0x39784500 RunWebThread(void*) + 440
10  libsystem_c.dylib               0x3b9a930e _pthread_start + 306
11  libsystem_c.dylib               0x3b9a91d4 thread_start + 4

Thread 4 name:  com.apple.NSURLConnectionLoader
Thread 4:
0   libsystem_kernel.dylib          0x3ba3feb4 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x3ba40048 mach_msg + 36
2   CoreFoundation                  0x337ff040 __CFRunLoopServiceMachPort + 124
3   CoreFoundation                  0x337fdd9e __CFRunLoopRun + 878
4   CoreFoundation                  0x33770eb8 CFRunLoopRunSpecific + 352
5   CoreFoundation                  0x33770d44 CFRunLoopRunInMode + 100
6   Foundation                      0x340bd3d0 +[NSURLConnection(Loader) _resourceLoadLoop:] + 304
7   Foundation                      0x34140e80 __NSThread__main__ + 968
8   libsystem_c.dylib               0x3b9a930e _pthread_start + 306
9   libsystem_c.dylib               0x3b9a91d4 thread_start + 4

Thread 5 name:  com.apple.CFSocket.private
Thread 5:
0   libsystem_kernel.dylib          0x3ba50594 __select + 20
1   CoreFoundation                  0x338031f2 __CFSocketManager + 674
2   libsystem_c.dylib               0x3b9a930e _pthread_start + 306
3   libsystem_c.dylib               0x3b9a91d4 thread_start + 4

Thread 6:
0   libsystem_kernel.dylib          0x3ba50d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x3b99ecf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x3b99ea12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x3b99e8a0 start_wqthread + 4

Thread 7:
0   libsystem_kernel.dylib          0x3ba50d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x3b99ecf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x3b99ea12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x3b99e8a0 start_wqthread + 4

Thread 8:
0   libsystem_kernel.dylib          0x3ba50d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x3b99ecf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x3b99ea12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x3b99e8a0 start_wqthread + 4

Thread 9:
0   libsystem_kernel.dylib          0x3ba50d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x3b99ecf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x3b99ea12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x3b99e8a0 start_wqthread + 4

Thread 10:
0   libsystem_kernel.dylib          0x3ba50d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x3b99ecf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x3b99ea12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x3b99e8a0 start_wqthread + 4

Unknown thread crashed with unknown flavor: 5, state_count: 1

通过谷歌搜索我找到了它，因为我正在将更新位置发送到已发布的对象。为此，我更改了 AppDelegate DidFinishlaunchingWithOptions

的代码

if ([CLLocationManager significantLocationChangeMonitoringAvailable]) {

//        if(!viewController.locationManager){
//            viewController.locationManager = [[CLLocationManager alloc] init];
//            viewController.locationManager.delegate = viewController;
//            viewController.locationManager.distanceFilter = 200.0f;
//            viewController.locationManager.desiredAccuracy = 200.0f;
//        }

        // Stop normal location updates and start significant location change updates for battery efficiency.
        viewController.locationManager.delegate = nil;
        [viewController.locationManager stopUpdatingLocation];
        viewController.locationManager.delegate = viewController;
        [viewController.locationManager startMonitoringSignificantLocationChanges];

        NSLog(@"significantLocationChangeMonitoringAvailable.");
    }
    else {

        NSLog(@"Significant location change monitoring is not available.");
    }

这是我要走的正确方式吗？还是崩溃日志指示其他内容？

【问题讨论】：

配置了您的 info.plist？在模拟器或设备中测试？
我已经用密钥Required Background Modes配置了info.plist -> App registers for location updates
使用设备进行测试。我已经从后台删除了应用程序，然后在我四处漫游以获取位置更新之后。但没有让我的应用程序在后台重新启动

标签： iphone objective-c core-location cllocationmanager cllocation

【解决方案1】：

目前，您应用的定位行为取决于您的viewController 是否可用。您已经组合了 MVC 的“V”和“C”部分。我会考虑将CLLocationManager 从您的视图控制器中拉出并将其设置为您的 AppDelegate 上的属性。这样你就不必实例化视图控制器来响应位置变化，它建立了一个模式来访问你应用程序中其他地方的位置。首先配置您的locationMananger，然后将其传递给您的viewController。

【讨论】：

【解决方案2】：

应用代理

(void)applicationDidBecomeActive:(UIApplication *)application
{

    if ([CLLocationManager significantLocationChangeMonitoringAvailable]) {

        [viewController.locationManager stopMonitoringSignificantLocationChanges];
    }

    if ([CLLocationManager locationServicesEnabled])
    {

        [viewController.locationManager startUpdatingLocation];
    }

}

(void)applicationDidEnterBackground:(UIApplication *)application
{

    [viewController.locationManager stopUpdatingLocation];
    [viewController.locationManager startMonitoringSignificantLocationChanges];



}

ViewController.m

locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.pausesLocationUpdatesAutomatically = NO;
locationManager.distanceFilter = 300;
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
[locationManager startUpdatingLocation];

【讨论】：