iOS 9 Background Location update and Update on server using web-service

Question

I have developed an application that has the capability to update the location on server while application is in background as well as foreground. I have used Timer which continuously updates location with 1 minute time interval, because if the interval is more than 1 minute , iOS suspends the application in background.

The problem is with iOS 9, when application is in background, some time it stops the location update and after some random time duration it again starts.

These are the crash logs which I found from device logs.

Exception Type:  00000020
    Exception Codes: 0x000000008badf00d
    Exception Note:  SIMULATED (this is NOT a crash)
    Highlighted by Thread:  2

    Application Specific Information:
    <BKNewProcess: 0x15646220; com.com.com; pid: 1168; hostpid: -1> has active assertions beyond permitted time: 
    {(
        <BKProcessAssertion: 0x15537b80> id: 1168-1B744B09-0EB7-4B01-A6FE-F167669E4439 name: Called by UIKit, from <redacted> process: <BKNewProcess: 0x15646220; com.com.com; pid: 1168; hostpid: -1> permittedBackgroundDuration: 180.000000 reason: finishTask owner pid:1168 preventSuspend  preventIdleSleep  preventSuspendOnSleep ,
        <BKProcessAssertion: 0x15643480> id: 1168-59515322-D982-46F8-94A5-0DD259406664 name: Called by UIKit, from <redacted> process: <BKNewProcess: 0x15646220; com.com.com; pid: 1168; hostpid: -1> permittedBackgroundDuration: 180.000000 reason: finishTask owner pid:1168 preventSuspend  preventIdleSleep  preventSuspendOnSleep 
    )}
    Elapsed total CPU time (seconds): 6.880 (user 6.880, system 0.000), 9% CPU 
    Elapsed application CPU time (seconds): 0.081, 0% CPU

Note: Everything is working completely fine in iOS 7 and iOS 8.

I have tried couple of solutions available on stackoverflow but I am not able to figure out the exact solutions which can solve the problem.

Also I found that if I don't lock the device then the location update and web-service calling works fine but if the device is locked, it stops updating location and calling up web-service.

Any help would be highly appreciated.

Thank you in advance.

UPDATE

AppDelegate.h

@property (nonatomic, retain) CLLocation *currentLocation;
@property (nonatomic, strong) NSTimer* locationUpdateTimer;
-(void)updateUsersLocation;
-(void)distroyTimer;

AppDelegate.m

-(void)callLocationManager
{
    @autoreleasepool
    {
        UIAlertView * alert;
        //We have to make sure that the Background App Refresh is enable for the Location updates to work in the background.
        if([[UIApplication sharedApplication] backgroundRefreshStatus] == UIBackgroundRefreshStatusDenied)
        {
            alert = [[UIAlertView alloc]initWithTitle:ALERTTITLE
                                              message:@"The app doesn't work without the Background App Refresh enabled. To turn it on, go to Settings > General > Background App Refresh"
                                             delegate:nil
                                    cancelButtonTitle:@"Ok"
                                    otherButtonTitles:nil, nil];
            [alert show];
            return;
        }
        else if([[UIApplication sharedApplication] backgroundRefreshStatus] == UIBackgroundRefreshStatusRestricted)
        {
            alert = [[UIAlertView alloc]initWithTitle:ALERTTITLE
                                              message:@"The functions of this app are limited because the Background App Refresh is disable."
                                             delegate:nil
                                    cancelButtonTitle:@"Ok"
                                    otherButtonTitles:nil, nil];
            [alert show];
            return;
        }
        else if(![CLLocationManager locationServicesEnabled])
        {
            UIAlertView *alert = [[UIAlertView alloc]
                                  initWithTitle:@""
                                  message:@"Please enable GPS service for HiHo Mobile From settings"
                                  delegate:nil
                                  cancelButtonTitle:@"OK"
                                  otherButtonTitles:nil];
            [alert show];
            return;
        }
        else
        {
            if (!self.locationManager)
            {
                self.locationManager = [[CLLocationManager alloc] init];
            }
            self.locationManager.delegate = self;
            // self.locationManager.distanceFilter = kCLDistanceFilterNone;
            self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
            self.locationManager.distanceFilter = 10.0f;
            self.locationManager.activityType = CLActivityTypeAutomotiveNavigation;

            if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)
            {
                [self.locationManager requestAlwaysAuthorization];
            }

            if ([self.locationManager respondsToSelector:@selector(allowsBackgroundLocationUpdates)])
            {
                self.locationManager.allowsBackgroundLocationUpdates  = YES;
            }
            if ([self.locationManager respondsToSelector:@selector(pausesLocationUpdatesAutomatically)])
            {
                self.locationManager.pausesLocationUpdatesAutomatically= NO;
            }
            if([self.locationManager respondsToSelector:@selector(allowsBackgroundLocationUpdates)])
            {
                [self.locationManager setAllowsBackgroundLocationUpdates:YES];
            }
            [self.locationManager stopMonitoringSignificantLocationChanges];
            [self.locationManager startUpdatingLocation];

            if ([USERDEFAULTS boolForKey:@"someFlag"]==YES)
            {
                [self distroyTimer];
                self.locationUpdateTimer =
                [NSTimer scheduledTimerWithTimeInterval:180
                                                 target:self
                                               selector:@selector(updateUsersLocation)
                                               userInfo:nil
                                                repeats:YES];
                [[NSRunLoop mainRunLoop]addTimer:self.locationUpdateTimer forMode:NSRunLoopCommonModes];
            }
            else
            {
                [self.locationManager stopUpdatingLocation];
                [self.locationManager startMonitoringSignificantLocationChanges];
            }
        }
    }
}

-(void)distroyTimer
{
    if ([self.locationUpdateTimer isValid])
    {
        [self.locationUpdateTimer invalidate];
        self.locationUpdateTimer = nil;
    }
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    NSLog(@"latitude: %f, longitude: %f",newLocation.coordinate.latitude, newLocation.coordinate.longitude);
    self.currentLocation = newLocation;
}

// Write your code to update location on server

-(void)updateUsersLocation
{
    // Your code goes here.
}

Note: Continuous update of location services will dramatically drain your iOS device's battery. So as soon as you have no use of updated location you can use significant locations .

Answer 1

您应该使用位置更新后台模式在后台获取位置更新，然后当调用didupdalocation时，您的应用程序将从后台唤醒请参阅文档以便更好地理解。

Answer 2

I had the same issue.

The new allowsBackgroundLocationUpdates can't stay at plist, you must put it in code.

myLM = [[CLLocationManager alloc] init];
if([myLM respondsToSelector:@selector(allowsBackgroundLocationUpdates)]) {
   [myLM setAllowsBackgroundLocationUpdates: YES];
}

Answer 3

I have kept a timer for starting and stopping the location manager, as I have posted a same question to apple developers and they suggest me to keep a single location manager for application and remove the timers which might gets affected during threads while application works in background , so finally I have removed the timers logic , and now location manager continuously updates the location until the user gets logged out. This might drain the battery but this one is the only solutions that I found and which is working for our application.