React-native 应用程序永远不会重新启动以处理 iOS 中的位置更新

Posted 2023-03-15

【中文标题】React-native 应用程序永远不会重新启动以处理 iOS 中的位置更新

【英文标题】：React-native app is never relaunched to handle location updates in iOS

【发布时间】：2017-10-30 19:59:22

【问题描述】：

我正在尝试在应用终止时在 react-native 应用中处理位置更新。经过几天未能让react-native-background-geolocation 或 CLLocationManager 始终如一地工作，我现在尝试使用intuit/LocationManager pod，但我的应用程序没有重新启动以响应位置更新（或者它只是没有记录它们？ )

这是 Intuit 处理基于位置的启动的示例：

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

    // If you start monitoring significant location changes and your app is subsequently terminated, the system automatically relaunches the app into the background if a new event arrives.
    // Upon relaunch, you must still subscribe to significant location changes to continue receiving location events. 
    if ([launchOptions objectForKey:UIApplicationLaunchOptionsLocationKey]) 
        INTULocationManager *locMgr = [INTULocationManager sharedInstance];
        [locMgr subscribeToSignificantLocationChangesWithBlock:^(CLLocation *currentLocation, INTULocationAccuracy achievedAccuracy, INTULocationStatus status) 
            // This block will be executed with the details of the significant location change that triggered the background app launch,
            // and will continue to execute for any future significant location change events as well (unless canceled).
        ];
    
    return YES;

这是我的代码：

- (BOOL) application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
  NSLog(@"--- Initializing application");

  INTULocationManager *locMgr = [INTULocationManager sharedInstance];
  [locMgr subscribeToSignificantLocationChangesWithBlock:^(CLLocation *currentLocation, INTULocationAccuracy achievedAccuracy, INTULocationStatus status) 
    // This block will be executed with the details of the significant location change that triggered the background app launch,
    // and will continue to execute for any future significant location change events as well (unless canceled).
    NSLog(@"--- location update");
  ];

  _app = application;

  id<RCTBridgeDelegate> moduleInitialiser = self;
  RCTBridge *bridge = [[RCTBridge alloc] initWithDelegate:moduleInitialiser launchOptions:launchOptions];

  RCTRootView *rootView = [[RCTRootView alloc]
    initWithBridge:bridge
    moduleName:@"GoNote"
    initialProperties:nil
  ];
  rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];
  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
  UIViewController *rootViewController = [UIViewController new];
  rootViewController.view = rootView;
  self.window.rootViewController = rootViewController;
  [self.window makeKeyAndVisible];

  [FIRApp configure];
  [[UNUserNotificationCenter currentNotificationCenter] setDelegate:self];

  return YES;

为了测试这一点，我在模拟器中打开应用程序，等待位置更新（应用程序记录“位置更新”），然后关闭应用程序（双击 command-shift-h 并滑开应用程序）。然后我等待模拟器的调试位置设置为“高速公路驱动器”。

据我了解，应用程序应该在后台启动，我应该看到日志“正在初始化应用程序”和“位置更新”，但这从未发生过。

我的info.plist 文件中有这些条目：

<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string>CHANGEME: NSLocationAlwaysAndWhenInUseUsageDescription</string>
<key>NSLocationAlwaysUsageDescription</key>
<string>CHANGEME: NSLocationAlwaysUsageDescription</string>
<key>NSLocationWhenInUseUsageDescription</key>
<string>CHANGEME: NSLocationWhenInUseUsageDescription</string>
<key>NSMotionUsageDescription</key>
<string>CHANGEME: NSMotionUsageDescription</string>
<key>UIBackgroundModes</key>
<array>
    <string>fetch</string>
    <string>remote-notification</string>
    <string>location</string>
</array>

为什么我的应用不处理位置更新？

【问题讨论】：

你能得到这个工作吗？我将时间花在完全相同的场景中。

【参考方案1】：

ios 有几个选项可以在后台正确运行应用程序。这些方法在 iOS 中启用。我们将使用您的应用程序将使用且我们需要的那个。我们可以在 UIBackgroundModes 数组中看到的所有服务：

点击此链接：- https://developer.apple.com/documentation/corelocation/cllocationmanager/1620568-allowsbackgroundlocationupdates?language=objc

如果应用程序在前台，我们可以简单地停止监视并在间隔后重新启动它，例如使用 NSTimer。在这种情况下，我们必须考虑应用程序的生命周期。应用程序在后台运行，空闲时停止工作。

在 iOS 原生中，我们无法更改系统更新用户位置的时间间隔。如果有 GPS 信号，IOS 会每秒定期更新位置。

应用程序每 5 分钟更新一次后台位置，请执行以下操作：

转到您的项目“目标”-> 功能-> 后台模式-> 选择位置更新

我的最后一个过程是在后台使用 NSTimer，方法是使用 UIApplication:beginBackgroundTaskWithExpirationHandler:。此计时器会在应用程序在后台运行时定期触发。

现在，当您的应用在后台时，让定位工作，并将坐标发送到网络服务或每 5 分钟对它们执行任何操作，如下面的代码所示。

AppDelegate.m

//update location
-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
 
     NSLog(@"Location: %f, %f", newLocation.coordinates.longtitude, newLocation.coordinates.latitude);
 

//run background task
-(voud)runBackgroundTask: (int) time

     //check if application is in background mode
     if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) 
     
          //create UIBackgroundTaskIdentifier and create tackground task, which starts after time
            __block UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:^
           [app endBackgroundTask:bgTask];
              bgTask = UIBackgroundTaskInvalid;
            ]; 

          dispatch_async(dispatch_get_global_queue (DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^

           NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(startTrackingBg) userInfo:nil repeats:NO];
          [[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
          [[NSRunLoop currentRunLoop] run];

          );
       
 

 //starts when application switchs into backghround
- (void)applicationDidEnterBackground:(UIApplication *)application

    //check if application status is in background
    if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) 
    
        NSLog(@"start backgroun tracking from appdelegate");

        //start updating location with location manager
        [locationManager startUpdatingLocation];
     

     //change locationManager status after time
     [self runBackgroundTask:20];


 //starts with background task
 -(void)startTrackingBg
     //write background time remaining
     NSLog(@"backgroundTimeRemaining: %.0f", [[UIApplication sharedApplication] backgroundTimeRemaining]);
     //set default time
     int time = 60;
     //if locationManager is ON
     if (locationStarted == TRUE ) 
         //stop update location
         [locationManager stopUpdatingLocation];
         locationStarted = FALSE;
     else
          //start updating location
          [locationManager startUpdatingLocation];
          locationStarted = TRUE;
          //ime how long the application will update your location
          time = 5;
    
   [self runBackgroundTask:time];
 

//application switchs back from background
 - (void)applicationWillEnterForeground:(UIApplication *)application
 
      locationStarted = FALSE;
      //stop updating
      [locationManager stopUpdatingLocation];
 

【讨论】：

为什么这么复杂？为什么必须在 didEnterBackground 生命周期方法中检查应用是否在后台？当应用程序在前台时，applicationDidEnterBackground 会被调用吗？为什么在applicationDidEnterBackground 中调用startUpdatingLocation，然后在20 秒后在startTrackingBg 中再次调用它？为什么停止startTrackingBg 中的位置更新？当您提到“背景”时，是否包括应用程序终止的时间？