I have an app where the user can gps-track his activities.
Everything works as expected with background GPS updates, but there are very rare cases (1 out of 1000), where I am just not receiving update calls from CLLocationManager when my app is in background. Not immediately, but after some time.
My app starts receiving updates and then all of a sudden (can be a couple of minutes or hours of tracking) it just won't get any more locations updates. It continues reporting location as soon as the app get's active again. But of course those missing locations are bad!
I didn't figure out when and why it happens, that's why I wanted to ask if somebody else already experienced the same issue? I can say that it's not a phone call or something like that that is interrupting. I also don't get callbacks in the didFail delegate method. I just don't get anything any more....
And the big problem is that I have NO IDEA on how to debug that, as I can't reproduce it on purpose.
Any help is very much appreciated.
EDIT:
Here's how I setup my location Manager
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.distanceFilter = kMinimumDistanceFilter;
self.locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
self.locationManager.pausesLocationUpdatesAutomatically = NO;
self.locationManager.activityType = CLActivityTypeFitness;
[self.locationManager requestWhenInUseAuthorization];
[self.locationManager requestAlwaysAuthorization];
if ([self.locationManager respondsToSelector:#selector(setAllowsBackgroundLocationUpdates:)])
{
self.locationManager.allowsBackgroundLocationUpdates = YES;
}
and then later when the Start-Recording-Button is hit
[self.locationManager startUpdatingLocation];
EDIT 2:
If you start this service and your app is suspended, the system stops
the delivery of events until your app starts running again (either in
the foreground or background). If your app is terminated, the delivery
of new location events stops altogether. Therefore, if your app needs
to receive location events while in the background, it must include
the UIBackgroundModes key (with the location value) in its Info.plist
file.
I don't even startUpdatingLocation in the background... But it seems as if that's what happening to my app. How would I be even able to start tracking if the app is suspended? That's impossible, isn't it? Cause suspended would mean it's not executing code?!?
Do you have allowsBackgroundLocationUpdates set to YES in your Info.plist?
From documentation:
By default, this is NO for applications linked against iOS 9.0 or
later, regardless of minimum deployment target.
With UIBackgroundModes set to include "location" in Info.plist, you
must also set this property to YES at runtime whenever calling
-startUpdatingLocation with the intent to continue in the background.
Setting this property to YES when UIBackgroundModes does not include
"location" is a fatal error.
Resetting this property to NO is equivalent to omitting "location"
from the UIBackgroundModes value. Access to location is still
permitted whenever the application is running (ie not suspended), and
has sufficient authorization (ie it has WhenInUse authorization and is
in use, or it has Always authorization). However, the app will still
be subject to the usual task suspension rules.
See -requestWhenInUseAuthorization and -requestAlwaysAuthorization for
more details on possible authorization values.
Related
I have a fitness app that receives location updates and has been working fine in the background since iOS 4. I just noticed that the location updates now stop when the app moves to the background (switching apps or locking the device) in iOS 10. I haven't found any notices of changes to functionality or background privileges; does anyone know what's happening?
My location setup is pretty basic:
if (!self.locationManager) {
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.distanceFilter = kCLDistanceFilterNone;
self.locationManager.activityType = CLActivityTypeFitness;
self.locationManager.pausesLocationUpdatesAutomatically = TRUE;
}
// request permissions on iOS 8+
if ([self.locationManager respondsToSelector:#selector(requestWhenInUseAuthorization)]) {
[self.locationManager requestWhenInUseAuthorization];
}
Then this callback receives updates:
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
DLog(#"didUpdateToLocation");
}
Everything is good when the app is in the foreground. As soon as it moves to the background, this messages appears in the console:
/BuildRoot/Library/Caches/com.apple.xbs/Sources/ExternalAccessory/ExternalAccessory-353.22.1/EAAccessoryManager.m:__52-[EAAccessoryManager _checkForConnectedAccessories:]_block_invoke-785 ending background task
Then updates stop. When I bring the app to the foreground, they resume again.
I'm not directly using EAAccessoryManager and can only guess what it is. I am using the BluetoothLE framework to receive data from heart rate monitors, but when I disable this functionality (stop instantiating a BluetoothLE object) the problem remains.
My UIBackgroundModes were set to location, external-accessory and bluetooth-central because I also have Pebble watch connectivity. I tried adding bluetooth-peripheral but that didn't help. I also have NSLocationWhenInUseUsageDescription and NSBluetoothPeripheralUsageDescription set and those are working.
A new property was added to CLLocationManager in iOS 9 - allowsBackgroundUpdates. This property defaults to false and must be explicitly set to true if you want to receive location updates in the background.
Apps that were built against the iOS 8 SDK received grandfathered functionality and continued to receive background updates even without setting this property.
I am trying to make an app to track the user GPS all the time, this app is a kind of car GPS tracker to get the location of driver all the time and send it to server.
I have tried to add "location updates" to the "background modes" but the app will automatically suspends after 10 mins when going into background.
Is there a way to make this app run all the time and get the GPS location?
You have two options here:
1) Regular location tracking. This type of tracking works with kCLAuthorizationStatusAuthorizedWhenInUse and kCLAuthorizationStatusAuthorizedAlways authorizations. When CLLocationManager started tracking location once it will receive location updates in delegate method locationManager:didUpdateLocations:. App can go to suspended state, but when location manager receive new location app goes to background state and handles new location in delegate method. How to setup location manager:
- (void)viewDidLoad {
[super viewDidLoad];
self.locationManager = [[CLLocationManager alloc] init];
// Setup location tracker accuracy
self.locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
// Distance filter
self.locationManager.distanceFilter = 50.f;
// Assign location tracker delegate
self.locationManager.delegate = self;
// This setup pauses location manager if location wasn't changed
[self.locationManager setPausesLocationUpdatesAutomatically:YES];
// For iOS9 we have to call this method if we want to receive location updates in background mode
if([self.locationManager respondsToSelector:#selector(allowsBackgroundLocationUpdates)]){
[self.locationManager setAllowsBackgroundLocationUpdates:YES];
}
[self.locationManager startUpdatingLocation];
}
2) Signification location changes tracking. This type of tracking works only with kCLAuthorizationStatusAuthorizedAlways authorization. It receives new location only each 500 meters, so distance filter and desiredAccuracy don't work here. App can go to suspended state, and even can be terminated by system, but when location updates app goes to background state and receives location in delegate method locationManager:didUpdateLocations:.If app was terminated by system, it will be relaunched in background with UIApplicationLaunchOptionsLocationKey key in launch options in didFinishLaunchingWithOptions app delegate method. How to setup this type on tracking:
- (void)viewDidLoad {
[super viewDidLoad];
self.locationManager = [[CLLocationManager alloc] init];
// Assign location tracker delegate
self.locationManager.delegate = self;
// For iOS9 we have to call this method if we want to receive location updates in background mode
if([self.locationManager respondsToSelector:#selector(allowsBackgroundLocationUpdates)]){
[self.locationManager setAllowsBackgroundLocationUpdates:YES];
}
[self.locationManager startMonitoringSignificantLocationChanges];
}
You should notice that both of these methods does not guarantee that your application does not go to suspended state.
Also, if app was terminated by user (for example from app switcher by swipe) location tracking in background will not work.
UPDATE (corresponding to comments)
Here is my code examples that work for me:
For Regular tracking. Run the example, provide access to user location, tap Start button to start location updates. To test locations in simulator choose in simulator menu Debug > Location > Freeway Drive. Now you can push app to background by home button (Command+Shift+H). Leave simulator for more than 10 minutes, and all this time app will receive locations. When you return to app you will see red pins on the map.
For Significant changes. Run the app and test by the same way as for previous example.
Monitoring Significant changes can be started only by method [self.locationManager startMonitoringSignificantLocationChanges];
UPDATE (iOS 11)
Changes to location tracking in iOS 11
iOS 11 also makes some major changes to existing APIs. One of the affected areas is location tracking. If your app only uses location while the app is in the foreground, as most apps do, you might not have to change anything at all; however, if it’s one of those apps that continuously track user’s location throughout the day, you should probably book some time this summer for making some changes in how you do the tracking and testing possible usage scenarios.
follow this link: https://mackuba.eu/2017/07/13/changes-to-location-tracking-in-ios-11/
I am sure it is useful for the author because the question was asked in Feb 2016 and I am giving an answer in June 2019. This answer maybe is useful for other users.
Recently, I was working with the same requirement. After 2-3 week hard work, I did it. For other users, I create a helper class for it. Which is available in GitHub.
Please use HSLocationManager for your requirement. I have achieved the same requirements in one of my project
Location manager that allows getting background location updates every
n seconds with desired location accuracy.
Advantage:
OS will never kill our app if the location manager is currently
running.
Give periodically location update when it required(range is between 2 -
170 seconds (limited by max allowed background task time))
Customizable location accuracy and time period.
Low memory consumption(Singleton class)
In reply to comment 1 in the solution (I can't comment anywhere yet): you didn't seem to solve the problem as your app gets suspended and doesn't update the location any more after 10 minutes.
I had the same issue: I had set setAllowsBackgroundLocationUpdates to YES, and I had the NSLocationAlwaysUsageDescription key in my Info.plist, but my App also used to stop tracking location after 10 minutes.
I solved it by adding both NSLocationAlwaysUsageDescription and NSLocationWhenInUseUsageDescription to the Info.plist file so it looks like this:
<key>NSLocationAlwaysUsageDescription</key>
<string>This app needs to use your location</string>
<key>NSLocationWhenInUseUsageDescription</key>
<string>This app needs to use your location</string>
set it.it take power of battery but your application run in Background.OS does not Suspend your App
[self.locationManager setPausesLocationUpdatesAutomatically:NO];
I am looking into using deferred location updates for an iOS activity tracker, which allows location services in background. I've implemented the suggested code snippets (see below). In Xcode debugging, deferred locations attempt to start a few times until location data comes in at about 1 per second. After that, it claims to succeed in starting deferrals, and the callback for the finish trigger also succeeds after the specified time period expires. However during the time, the location handler still runs once per second. I've read that this is because the phone hasn't deemed itself ready to enter the background, and that testing in Xcode does this. Note, AppDelegate's "didEnterBackground" eventhandler got called immediately when turning off the screen, and resumed when reopening app.
I ran the same code with the phone disconnected as another test, near the window with GPS, screen off, or switching to entirely different apps, and it still never actually defers the updates. I can tell because the networked update still comes in once every 30 seconds, instead of the interval of 120 seconds which is desired in the code sample below.
What else is needed to actually get deferrals to work, since there is no error occurring in starting them and they do get their finish callback? Why do location updates continue at 1 per second even when the app goes to background?
Iphone 5s, IOS 7.1.1
// .h file (partial)
#interface MotionTracker : NSObject<CLLocationManagerDelegate, UIAccelerometerDelegate>
#property (strong, nonatomic) CLLocationManager *locationManager;
#end
// .m file (parial)
- (id) init {
if(self = [super init]){
_locationManager = [[CLLocationManager alloc] init];
_locationManager.delegate = self;
_locationManager.distanceFilter = kCLDistanceFilterNone;
_locationManager.desiredAccuracy = kCLLocationAccuracyBest;
// if set to YES (default), app stops logging location at some point and doesn't resume in any timely fashion, all data points lost in between
_locationManager.pausesLocationUpdatesAutomatically = NO;
_locationManager.activityType = CLActivityTypeFitness;
}
return self;
}
// called early in program after login confirmed
- (void) startCollectingLocation {
[_locationManager startUpdatingLocation];
}
- (void)locationManager:(CLLocationManager *)manager
didUpdateLocations:(NSArray *)locations {
// logs to file when device is not in debug
// always returns 1
NSLog(#"Location update count: %d",[locations count]);
// some code here to handle location updates
// - collect key location day in NSDictionary
// - every N seconds send Network call to server to save (have tried 30 seconds, 15 minutes, 30 minute network intervals). Have also tried turning off network calls completely.
// deferred updates starter
if (!self.deferringUpdates) {
if([CLLocationManager deferredLocationUpdatesAvailable]){
[_locationManager allowDeferredLocationUpdatesUntilTraveled:500 timeout:(NSTimeInterval)120]; // (have also tried large numbers, and "Infinite"
self.deferringUpdates = YES;
NSLog(#"Deferred updates start");
} else {
NSLog(#"Deferred updates not available");
}
}
}
- (void)locationManager:(CLLocationManager *)manager didFinishDeferredUpdatesWithError:(NSError *)error {
if(!error){
_deferringUpdates = NO;
NSLog(#"Deferred updates: finished");
} else {
_deferringUpdates = NO;
NSLog(#"Deferred updates: %#", [error localizedDescription]);
}
}
If the device is connected to a debugger or on a charger, the device will remain powered (not sleep) and therefore will not enter deferred mode. Deferred mode is a power optimization allowing the device to sleep. If the device is not scheduled to sleep for other reasons, enabling deferred mode will not force it to sleep otherwise. Try your test by ensuring no other apps are using location services, and disconnecting it from a charger with the screen off. After running for some time, plug back in and check your logs, you should see that the device slept and deferred updates.
From Apple's
allowDeferredLocationUpdatesUntilTraveled:timeout: documentation:
Deferred updates are delivered only when the system enters a low power
state. Deferred updates do not occur during debugging because Xcode
prevents your app from sleeping and thus prevents the system from
entering that low power state.
It is also worth noting that deferred updates are only available when locationManager.desiredAccuracy is set to kCLLocationAccuracyBest OR kCLLocationAccuracyBest; locationManager.distanceFilter must also be set to kCLDistanceFilterNone.
From Apple's documentation:
...the location manager allows deferred updates only when GPS hardware is available on the device and when the desired accuracy is set to kCLLocationAccuracyBest or kCLLocationAccuracyBestForNavigation.
and
...the distanceFilter property of the location manager must be set to kCLDistanceFilterNone.
I have been struggling with the same issue, and I may have found an answer that solves this problem for many - at least it solves my problem and gets deferred updates working consistently for me.
I followed all of the steps in this list and no matter what I did, location updates would not defer. It occurred to me that I might have other apps running that were not allowing the system to sleep, so I killed all other apps in the multitasking tray. I ran my sample app again and ... it worked!
But the story doesn't end there. I tried again a little later, and even though there were no other apps running in the multitasking tray I couldn't get location services to defer. Then it occurred to me that I have an app on my phone called "Moves" which manages to keep itself alive even after you manually kill it. I'm not entirely sure how Moves comes magically back to life when you kill it, but it does (perhaps using bluetooth and the app preservation / restoration service). Even though it is alive and tracking your location it doesn't appear in the multitasking tray. I think that only apps that are manually launched appear in the tray - if the OS launches an app it doesn't appear in the tray. But I digress ...
I was able to get deferred location services to work consistently in my app by disallowing Moves to use location services. When I did, Moves complained even though it wasn't in multitasking tray. It seems that if another app is using location services (and not deferring) your app won't defer either.
Hi recently with the iOS 9 GM seed version out,I have seen location update(allowDeferredLocationUpdatesUntilTraveled:timeout:) not getting deferred.The same code used to work in iOS 8.4 and below versions.Its draining my device's battery by a huge margin.
Is there anything we need to explicitly set or mention for iOS 9?Didn't find anything from Apple documentation
Here is the code that I implemented.
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
if (!self.deferringUpdates) {
[self.locationManager allowDeferredLocationUpdatesUntilTraveled:CLLocationDistanceMax timeout:30];
self.deferringUpdates = YES;
} }
-(void)locationManager:(CLLocationManager *)manager didFinishDeferredUpdatesWithError:(NSError *)error { // Stop deferring updates self.deferringUpdates = NO;
}
I also set the allowsBackgroundLocationUpdates property but even that didn't help. self.locationManager.allowsBackgroundLocationUpdates=YES;
In iOS 9 and later, regardless of deployment target, you must also set the allowsBackgroundLocationUpdatesproperty of the location manager object to YES in order to receive background location updates. By default, this property is NO, and it should remain this way until a time when your app actively requires background location updates.
https://developer.apple.com/library/prerelease/ios/documentation/Performance/Conceptual/EnergyGuide-iOS/LocationBestPractices.html
Please let me know what additional I need to make
Thanks
My CLLocationManager starts when the user first enters the app. I am initializing it like this:
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.distanceFilter = kDistanceFilter;
self.locationManager.headingFilter = kHeadingFilter;
And I am using geofencing.
I have defined in my .plist the required background modes.
If I test the app in the simulator using a gpx file, it works fine. So far, so good.
However, I read in these two links:
Start Location Manager in iOS 7 from background task
Background Location Services not working in iOS 7
That in iOS7, when the location does not change for a couple of minutes then the CLLocation goes to sleep.
My question is that:
I do not call didUpdateLocation at all, I only want the didEnterRegion, or didExitRegion. Theoretically, will it work , even the app is killed or user Location has not changed in the last hour and then decides to move?
There are a few elements in your questions:
1- In order not to rehash what is in a previous answer, I would first look at my answer at this link. It will help you resolve around the core location updates stopping if the user stops moving and how you can modify that behaviour:
iOS7 Core Location not updating
2- If the user kills an app in iOS7 (by flicking it up in the app switcher), the app will not restart and as such neither your location updates nor region monitoring will restart after the phone is restarted. On the other hand, if the app is killed because of memory pressures, iOS will restart the app and relaunch your location updates and region monitoring in the background. Also, if you reboot the phone, region monitoring will restart automatically. You obviously must have the background mode enabled.
3- Now you are talking about regions in your questions so I am assuming you have implemented CLCircularRegion. If not, that should be the first step and then "startMonitoringForRegion". In your case, even if the user has stopped moving for a while and then started moving, the app will be awaken/delegate called when the app enters or exit a region.
4- Make sure to use locationManager: didDetermineState: forRegion: as well. This will allow the app to determine if it is inside or outside of the region at start. This is useful when you think of an app being launched and no region crossing has happened but it is important to know whether the user is inside or outside of the region.
Hope this helps
I am failing to find any documentation on this. If my application is able to use background location services, how much processing can it really do before the device stops the task as its using too much resource?
E.g. When the location changes, I would like to ping my server with the new location.
Regards:
John
If an app has the permission of getting location updates in the background, then you are not limited on performing any tasks, so you could run any code, as the app is allowed to execute code while it is suspended (this is used by apps providing navigation).
However, be aware, that Apple will not approve your App, with the background Location updates permission, unless it's an App that would justify this requirement (Sports tracking App, Navigation App, etc)
You can get location updates from Region Monitoring or Significant Location changes, without having to use the location updates background mode.
So now comes the tricky part. Do I have enough time to perform a Server update of the users Location when my App is started from Background mode by the Region Monitoring or Significant Location services ?
The answer, seems to be yes, as suggested by this article
I haven't tried this, but judging by the code, I don't find a reason why this shouldn't work!
You will have to declare App’s Supported Background Tasks in info.plist
Under the information property list add array given format below:
Inforrmation Property list (Dictionary) ->
Required background modes (array) (1 item) ->
item 0 (String) - App registers for location updates
after these settings in info.plist you can do code which you want to do in background process at AppDelegate:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
/*
Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
*/
self.locationManager = [[CLLocationManager alloc] init];
_locationManager.delegate = self;
[_locationManager stopMonitoringSignificantLocationChanges];
[_locationManager startUpdatingLocation];
}
For more information you can visit:
Declaring Your App’s Supported Background Tasks