Android Tutorial Background location tracking

Simple example of a foreground service that keeps the process running in the background. The current location is shown in the persistent notification.

The app starts at boot and theoretically should run all the time. It also schedules itself to run with StartServiceAt. This can help in cases where the OS kills the process.

Relevant example, based on this example, which plays music in the background: https://www.b4x.com/android/forum/threads/background-task.111106/#post-693336

Updates:

- Project updated with targetSdkVersion = 34.
This update required several changes:

1. New non-dangerous permission:
   
   AddPermission(android.permission.FOREGROUND_SERVICE_LOCATION)
   With the above change the service can be started from the activity and run theoretically forever. However if we also want to start tracking after the device is booted then we need to follow several additional steps:
2. We need to receive the ACCESS_BACKGROUND_LOCATION permission. This is a special permission and it is granted in the settings app. We can only help the user get into the settings app - see Activity_Resume code.
3. The Tracker service can no longer be started after boot directly. This is related to the fact that we must make it a foreground service and it is impossible to do without the ACCESS_BACKGROUND_LOCATION permission. So the solution is to add a Receiver that starts after boot (see manifest editor), checks whether we have the permission and then starts the service with a call to StartForegroundService sub. Note that this sub doesn't actually moves the service to the foreground state. Instead it tells the system that the target service will be moved to the foreground. This is something that is required since Android 8 and in previous cases it was possible to manage it internally.

- Project updated with targetSdkVersion = 33 and the handling of the new post notifications permission.

 

[Multiverse app]

Hi,
How much important is to call

Private lock As PhoneWakeState
lock.PartialLock

How much more battery is consumed in the background after getting the partial lock?
Thanks.

 

[Multiverse app]

Also,

StartServiceAt(Me, DateTime.Now + 30 * DateTime.TicksPerMinute, True)

This means the service is scheduled to start every 30 seconds. right?

 

[Erel]

Partial lock: If you want to try and prevent the CPU from sleeping then acquire this lock. It doesn't have any effect when the device is not sleeping.

This means the service is scheduled to start every 30 seconds. right?

No. 30 * DateTime.TicksPerMinute.

 

[netsistemas]

Very important to do (don´t eliminate in sample):

Service.StartForeground(nid,  CreateNotification("..."))

in Service_Start event of Tracker service

else tracker service are destroyed.

 

[Multiverse app]

Also,
Just noticed that Service.StopForeground() is not called.
Does system handle it automatically, or is it just a programming error?

 

[netsistemas]

I believe that is the right thing. If the service that handles the notifications stops, the rest of services will do it automatically, which would be a big problem. I suppose if you want to stop the trace service, you must close first the notification service (close Notificacion lanch in StartForeGrond).
Excuse me and rejoice in my explanations. I'm not an expert on these issues.
Android 8+ is more automatic: close service (service starter ignored, but no others)

 

[Erel]

Does system handle it automatically, or is it just a programming error?

Neither. This app is intended to always run so it is never stopped. Call StopService(<service name which I don't remember>) if you want to stop it.

BTW, it is already running for 5 days here without any interruption.

 

[Erel]

Very important to do:

This is already implemented in the example.

 

[Christian García S.]

Hello @Erel,

I have a question, when you want to stop the service with StopService(Servicio) but you have:

StartServiceAt(Me, DateTime.Now + 30 * DateTime.TicksPerMinute, True)

The service will start again even when you stop service before, how I can do ? with variables ?

Thanks

 

[Erel]

Good question. You also need to call:

CancelScheduledService(Me)

 

[sentechnologies]

While compiling the above said MyLocation Project am receiving the following error

Spoiler: Error

B4A Version: 8.80 BETA #1
Parsing code. (0.00s)
Building folders structure. (0.02s)
Compiling code. (0.01s)
Compiling layouts code. (0.00s)
Organizing libraries. (0.00s)
Generating R file. Error
ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:fontVariationSettings
ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:ttcIndex

 

[DonManfred]

While compiling the above

1. You should always start a new thread for your questions.
2. Use the b4a sdk manager and update all recommeded items.
3. Use Android.jar from Platform 28

 

[Erel]

I've updated the example and removed the StartServiceAt call as it is no longer allowed to start services when the app is in the background (except of a few special cases).

 

[Erel]

- Project updated with targetSdkVersion = 33 and the handling of the new post notifications permission.

 

[Erel]

Project updated with targetSdkVersion = 34. See first post for more details.