Long running Background task Stopped Periodically iOS - ios

Question

In My Application.
I used following code to Update Location Coordinates to Server with 1 min time Interval. Its working fine for some times 10 to 20 Hours. but its some time stopped Periodically Please help me.
UIApplication *application1 = [UIApplication sharedApplication];
__block UIBackgroundTaskIdentifier background_task;
background_task = [application1 beginBackgroundTaskWithExpirationHandler:^ {
[application1 endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
//### background task starts
//NSLog(#"Running in the background\n");
while(TRUE)
{
[locationManager startMonitoringSignificantLocationChanges];
[locationManager startUpdatingLocation];
NSUserDefaults *addValue=[NSUserDefaults standardUserDefaults];
NSString *oldLat=[addValue stringForKey:#"OLD_LAT"];
NSString *oldLong=[addValue stringForKey:#"OLD_LONG"];
CLLocationManager *manager = [[CLLocationManager alloc] init];
manager.desiredAccuracy=kCLLocationAccuracyBestForNavigation;
NSString *locLat = [NSString stringWithFormat:#"%lf",manager.location.coordinate.latitude];
NSString * locLong = [NSString stringWithFormat:#"%lf",manager.location.coordinate.longitude];
float lat_new=[locLat floatValue];
float lang_new=[locLong floatValue];
float lat_old=[oldLat floatValue];
float lang_old=[oldLong floatValue];
if (lat_new>0 && lang_new>0) {
//NSLog(#"location changed");
[addValue setObject:locLat forKey:#"OLD_LAT"];
[addValue setObject:locLong forKey:#"OLD_LONG"];
float from_lat_value=[locLat floatValue];
float from_long_value=[locLong floatValue];
locLat=[NSString stringWithFormat:#"%f",from_lat_value];
locLong=[NSString stringWithFormat:#"%f",from_long_value];
//NSLog(#"LST:%#,%#",locLat,locLong);
NSUserDefaults *addLat=[NSUserDefaults standardUserDefaults];
[addLat setObject:locLat forKey:#"FROM_LAT"];
[addLat setObject:locLong forKey:#"FROM_LONG"];
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:#"%#/user/insertUserLocation",CONFIG_BASE_URL]];
// //NSLog(#"URL:%#",url);
__block ASIFormDataRequest *requestmethod = [ASIFormDataRequest requestWithURL:url];
NSUserDefaults *userValue=[NSUserDefaults standardUserDefaults];
NSString *deviceToken=[NSString stringWithFormat:#"%#",[userValue objectForKey:#"DEVICE_TOKEN"]];
NSString *loginValidation=[userValue objectForKey:#"USER_ID"];
[requestmethod setValidatesSecureCertificate:NO];
[requestmethod setPostValue:deviceToken forKey:#"deviceToken"];
[requestmethod setPostValue:locLat forKey:#"latitude"];
[requestmethod setPostValue:locLong forKey:#"longitude"];
[requestmethod setPostValue:loginValidation forKey:#"userID"];
[requestmethod setTimeOutSeconds:180];
[requestmethod setCompletionBlock:^{
NSString *responseString23 = [requestmethod responseString];
//NSLog(#"BACKGROUND RESPONCE:%#",responseString23);
}];
[requestmethod setFailedBlock:^{
NSError *error = [requestmethod error];
if ([[NSString stringWithFormat:#"%#",error.localizedDescription] isEqualToString:#"The request timed out"]||[[NSString stringWithFormat:#"%#",error.localizedDescription] isEqualToString:#"Please connect online to use the app"])
{
}
else
{
UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:#"Alert-360"
message:[NSString stringWithFormat:#"%#",error.localizedDescription] delegate:self
cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alertView show];
}
// [self endBackgroundUpdateTask];
}];
[requestmethod startAsynchronous];
}
[locationManager stopMonitoringSignificantLocationChanges];
[locationManager stopUpdatingLocation];
}
[NSThread sleepForTimeInterval:BACKGROUND_INTERVAL_CHECKIN]; //wait for 1 sec
//Clean up code. Tell the system that we are done.
[application1 endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
//NSLog(#"background Task finished");
});

Answer 1

Check my commends.
After App Enters background, we can get Latitude and longitude values.but we can't post this data to server. Apple restricted this.
I calculated both Foreground and Background time remaining code, I got following results
Foreground:
Foreground time remaining >>>>: 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.000000 seconds (2147483647 mins)
Background:
Background time remaining >>>>: 159.223682 seconds (2 mins)
For my final commend: we can't run background location update to server long time.

Answer 2

I used to receive the same crashes in my gps trackers that run in the background. I fixed those crashes by checking the values validity before every call. I found some of my variables are nil. Calling selectors of null variables will most probably kick the execution outside the task function with no rescheduling.
Guarding my calls with a null check on every task call fixed my issue. You can also add as much logs as you can; and leave it running for a while and then check where the crash happen by checking your logs. Beside the normal nslog output I used to have an external shared document logging text file as well. You should be able to have all your application logs in that file separated at any time in the future. Make sure to turn that logging off before sending to market.