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  • Update location in background after specific interval of time in objecticeC

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    This blog includes updation of location while your app is in background mode. Sometimes we need to fetch the user location while the app is in a background. To achieve this first we need to use the location manager.

     

    Here is the code for run the background task.write this in your AppDelegate.m class.

    //run background task
    -(void)runBackgroundTask: (int) time{
        
        //func use to get the current location
        [self getCurrentLocation];
        
        //check if application is in background modeg
        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), ^{
                //schedule the timer
                NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(updateLocation) userInfo:nil repeats:NO];
                [[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
                [[NSRunLoop currentRunLoop] run];
            });
        }else if ([UIApplication sharedApplication].applicationState == UIApplicationStateActive)
        {
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
                NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(updateLocation) userInfo:nil repeats:NO];
                [[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
                [[NSRunLoop currentRunLoop] run];
            });
        }
    }
    

     

    Here is the code to get current location-

    
    //declare global location manager
    CLLocationManager *locationManager;
    UIApplication *app;

     

    Initialize location manager viewdidload()-

    //create CLLocationManager variable
        locationManager = [[CLLocationManager alloc] init];
        
        if ([Utils isIos8]) {
            if ([locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
                [locationManager requestAlwaysAuthorization];
            }
            [locationManager requestAlwaysAuthorization];
        }
        
        //set delegate
        locationManager.delegate = self;
        
        app = [UIApplication sharedApplication];
    

     

    -(void)getCurrentLocation
    {
            [locationManager startUpdatingLocation];
            [locationManager setAllowsBackgroundLocationUpdates:YES];
    }

     

    Use the following code in appdelegate class-

    //starts when application switchs into background
    - (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
        }
        
        //change locationManager status after time.time is in seconds.
        //here it will update location after 5 minutes.
        [self runBackgroundTask:60*5];
        
    }

     

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