在iOS中后台运行应用程序时将用户位置发送到服务器

Question

Please help me i am trying to send my current location of app to server while my app is in background mode.

But after some time location update method is stops to get current location.

- (void)startLocationTracking
{
    NSLog(@"startLocationTracking");

    if ([CLLocationManager locationServicesEnabled] == NO)
    {
        NSLog(@"locationServicesEnabled false");
        UIAlertView *servicesDisabledAlert = [[UIAlertView alloc] initWithTitle:@"Location Services Disabled" message:@"You currently have all location services for this device disabled" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [servicesDisabledAlert show];
    } else
    {
        CLAuthorizationStatus authorizationStatus= [CLLocationManager authorizationStatus];

        if(authorizationStatus == kCLAuthorizationStatusDenied || authorizationStatus == kCLAuthorizationStatusRestricted){
            NSLog(@"authorizationStatus failed");
        } else {
            NSLog(@"authorizationStatus authorized");
            CLLocationManager *locationManager = [LocationTracker sharedLocationManager];
            locationManager.delegate = self;
            locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
            locationManager.distanceFilter = kCLDistanceFilterNone;

            if(IS_OS_8_OR_LATER) {
              [locationManager requestAlwaysAuthorization];
            }
            [locationManager startUpdatingLocation];
            [locationManager startMonitoringSignificantLocationChanges];
        }
    }
}


- (void)stopLocationTracking {
    NSLog(@"stopLocationTracking");

    if (self.shareModel.timer) {
        [self.shareModel.timer invalidate];
        self.shareModel.timer = nil;
    }

    CLLocationManager *locationManager = [LocationTracker sharedLocationManager];
    [locationManager stopUpdatingLocation];
    [locationManager stopMonitoringSignificantLocationChanges];
}

#pragma mark - CLLocationManagerDelegate Methods

-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{

    NSLog(@"locationManager didUpdateLocations");

    for(int i=0;i<locations.count;i++){
        CLLocation * newLocation = [locations objectAtIndex:i];
        CLLocationCoordinate2D theLocation = newLocation.coordinate;
        CLLocationAccuracy theAccuracy = newLocation.horizontalAccuracy;

        NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];

        if (locationAge > 30.0)
        {
            continue;
        }

        //Select only valid location and also location with good accuracy
        if(newLocation!=nil&&theAccuracy>0
           &&theAccuracy<2000
           &&(!(theLocation.latitude==0.0&&theLocation.longitude==0.0))){

            self.myLastLocation = theLocation;
            self.myLastLocationAccuracy= theAccuracy;

            NSMutableDictionary * dict = [[NSMutableDictionary alloc]init];
            [dict setObject:[NSNumber numberWithFloat:theLocation.latitude] forKey:@"latitude"];
            [dict setObject:[NSNumber numberWithFloat:theLocation.longitude] forKey:@"longitude"];
            [dict setObject:[NSNumber numberWithFloat:theAccuracy] forKey:@"theAccuracy"];

            //Add the vallid location with good accuracy into an array
            //Every 1 minute, I will select the best location based on accuracy and send to server
            [self.shareModel.myLocationArray addObject:dict];
        }
    }

    //If the timer still valid, return it (Will not run the code below)
    if (self.shareModel.timer) {
        return;
    }

    self.shareModel.bgTask = [BackgroundTaskManager sharedBackgroundTaskManager];
    [self.shareModel.bgTask beginNewBackgroundTask];

    //Restart the locationMaanger after 1 minute
    self.shareModel.timer = [NSTimer scheduledTimerWithTimeInterval:60 target:self
                                                           selector:@selector(restartLocationUpdates)
                                                           userInfo:nil
                                                            repeats:NO];

    //Will only stop the locationManager after 10 seconds, so that we can get some accurate locations
    //The location manager will only operate for 10 seconds to save battery
    if (self.shareModel.delay10Seconds) {
        [self.shareModel.delay10Seconds invalidate];
        self.shareModel.delay10Seconds = nil;
    }

    self.shareModel.delay10Seconds = [NSTimer scheduledTimerWithTimeInterval:10 target:self
                                                    selector:@selector(stopLocationDelayBy10Seconds)
                                                    userInfo:nil
                                                     repeats:NO];
}


//Stop the locationManager
-(void)stopLocationDelayBy10Seconds{
    CLLocationManager *locationManager = [LocationTracker sharedLocationManager];
    [locationManager stopUpdatingLocation];
    [locationManager stopMonitoringSignificantLocationChanges];

    NSLog(@"locationManager stop Updating after 10 seconds");
}


- (void)locationManager: (CLLocationManager *)manager didFailWithError: (NSError *)error
{
   NSLog(@"locationManager error:%@",error);
}


//Send the location to Server
- (void)updateLocationToServer {

    NSLog(@"updateLocationToServer");

    // Find the best location from the array based on accuracy
    NSMutableDictionary * myBestLocation = [[NSMutableDictionary alloc]init];

    for(int i=0;i<self.shareModel.myLocationArray.count;i++){
        NSMutableDictionary * currentLocation = [self.shareModel.myLocationArray objectAtIndex:i];

        if(i==0)
            myBestLocation = currentLocation;
        else{
            if([[currentLocation objectForKey:ACCURACY]floatValue]<=[[myBestLocation objectForKey:ACCURACY]floatValue]){
                myBestLocation = currentLocation;
            }
        }
    }
    NSLog(@"My Best location:%@",myBestLocation);

    //If the array is 0, get the last location
    //Sometimes due to network issue or unknown reason, you could not get the location during that  period, the best you can do is sending the last known location to the server
    if(self.shareModel.myLocationArray.count==0)
    {
        NSLog(@"Unable to get location, use the last known location");

        self.myLocation=self.myLastLocation;
        self.myLocationAccuracy=self.myLastLocationAccuracy;

    }else{
        CLLocationCoordinate2D theBestLocation;
        theBestLocation.latitude =[[myBestLocation objectForKey:LATITUDE]floatValue];
        theBestLocation.longitude =[[myBestLocation objectForKey:LONGITUDE]floatValue];
        self.myLocation=theBestLocation;
        self.myLocationAccuracy =[[myBestLocation objectForKey:ACCURACY]floatValue];
    }
    [self getUpdateLocation];
    NSLog(@"Send to Server: Latitude(%f) Longitude(%f) Accuracy(%f)",self.myLocation.latitude, self.myLocation.longitude,self.myLocationAccuracy);

    //TODO: Your code to send the self.myLocation and self.myLocationAccuracy to your server

    //After sending the location to the server successful, remember to clear the current array with the following code. It is to make sure that you clear up old location in the array and add the new locations from locationManager
    [self.shareModel.myLocationArray removeAllObjects];
    self.shareModel.myLocationArray = nil;
    self.shareModel.myLocationArray = [[NSMutableArray alloc]init];
}

-(void)getUpdateLocation
{
    NSUserDefaults *currentDefaults = [NSUserDefaults standardUserDefaults];

    dataMobile = [currentDefaults valueForKey:@"mobile"];
    dataCode = [currentDefaults valueForKey:@"code"];

    strMobile = [self getDecryptionMobile];
    strCode = [self getDecryptionCode];

    strToken = [NSString stringWithFormat:@"%@%@%@",@"Apple",strMobile,strCode];

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    manager.responseSerializer = [AFHTTPResponseSerializer serializer];

    NSDictionary *params = @ {@"function" :@"map/location/insert",@"childIdEnc":[currentDefaults valueForKey:@"childIdEnc"], @"phoneId" : [currentDefaults valueForKey:@"phoneId"], @"latitude": [NSString stringWithFormat:@"%f",self.myLocation.latitude], @"longitude": [NSString stringWithFormat:@"%f",self.myLocation.longitude]};
    NSLog(@"params %@",params);

    [manager POST:@"https://api.familyconnect.net/call/?debug=1" parameters:params
          success:^(AFHTTPRequestOperation *operation, id responseObject)
    {
        NSDictionary *jsonList = [NSJSONSerialization JSONObjectWithData:responseObject options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"JSON: %@", jsonList);
    }
          failure:
     ^(AFHTTPRequestOperation *operation, NSError *error) {
         NSLog(@"Error: %@", error);
     }];
}

I have use background fetch and location update in my app. also turn on it from settings->capabilities.

But when i am debugging from xcode and get app in background then its working properly but while i disconnect and test it then its stops updating my location.

Please help me guys.

Answer 1

It seems you are using code inspired by this example https://github.com/voyage11/Location

But this example stops the location updates after 10 seconds in order to save battery life. See this comment

//Will only stop the locationManager after 10 seconds, so that we can get some accurate locations
//The location manager will only operate for 10 seconds to save battery

But if configured correctly, the locationtracker also creates a timer in order to start the location updates again in 60 seconds.

Basically it collects location updates for 10 seconds, filters out the best. After 60 seconds location updates are starting again. In the link above please refere to the LocationAppDelegate calls

//Send the best location to server every 60 seconds
//You may adjust the time interval depends on the need of your app.
NSTimeInterval time = 60.0;
self.locationUpdateTimer =
[NSTimer scheduledTimerWithTimeInterval:time
                                 target:self
                               selector:@selector(updateLocation)
                               userInfo:nil
                                repeats:YES];

This timer leads to a "restart" of the location updates.