iOS Question How to use the BGTaskScheduler

[Alexander Stolte]

I would like to create an alarm clock app and have found apps in the app store that do exactly what I want to achieve.

e.g. ring in 8 hours, the apps regulate the volume in the background of the music that is then played -> so the app has to run in the background. I came across the following point in the documentation:

BGTaskScheduler | Apple Developer Documentation

A class for scheduling tasks that add background support to your app’s most critical work.

developer.apple.com

How can i use it in B4I?

 

[Erel]

BGTaskScheduler is not suitable for alarm clock app. It doesn't let you run a task at a specific time. It is similar to the "background fetch" feature.

You should use a local notification as an alarm.

 

[Alexander Stolte]

It doesn't let you run a task at a specific time.

But it must be possible somehow... I mean, there are also sleep tracking apps that run in the background all the time.

You should use a local notification as an alarm.

Unfortunately, this is not a solution. For example, I always have my phone on silent, so I would never hear the alarm and I also always have to make sure that I have the sound at a volume that I can hear. While the alarm clock apps regulate the volume while the music is playing.

Then I'll probably have to search a bit more

 

[Erel]

I mean, there are also sleep tracking apps that run in the background all the time.

Running in the background is not related to BGTaskScheduler.

There are several specific use cases which allow apps to run in the background. For example location tracking.

 

[Alessandro71]

have a look at this thread

PListExtra key value

Referring to this Background Modes: https://stackoverflow.com/questions/57197958/what-is-the-xcode-background-processing-background-mode/66390232#66390232 I've been able to identify the UIBackgroundModes keys for "audio", "location" and "fetch", but not for the "Background Processing Task" mode...

www.b4x.com

 

[Alexander Stolte]

have a look at this thread

Did you get it to work?

 

[Alessandro71]

Did you get it to work?

my use case was not about scheduling task rather than having the app not suspended upon going in background.
apparently it allows the app to run even while not in foreground.
i don't know for how long though, since for my app need only some minutes

 

[Alexander Stolte]

apparently it allows the app to run even while not in foreground.

thats excatly what i need. all the alarm clock apps only work if the task has not been killed

 

[Alexander Stolte]

Did you use the same code as for fetch and only changed the "processing" in the plist declaration instead of "fetch"?

 

[Alessandro71]

this is the code I use for plist

#PlistExtra: <key>BGTaskSchedulerPermittedIdentifiers</key>
#PlistExtra: <array>
#PlistExtra:   <string>package.name.here</string>
#PlistExtra: </array>
#PlistExtra: <key>UIBackgroundModes</key>
#PlistExtra: <array>
#PlistExtra:   <string>bluetooth-central</string>
#PlistExtra:   <string>processing</string>
#PlistExtra: </array>

no other events/subs defined

 

[Alexander Stolte]

this is the code I use for plist

Thanks this works togehter with #PlistExtra: <string>audio</string>

 

[Alexander Stolte]

But somehow the whole thing only works in the IOS simulator. Nothing happens on my Iphone when the app is in the background. I have already switched to VideoPlayer. But even the timer that controls the whole thing is only triggered when I bring the app back into the foreground. It works reliably in the simulator...

 

[Alexander Stolte]

Solution:

AS Alarm - Alarm clock or keep app active in the background

I needed a way to play a sound at a certain time even though the app is in the background. The problem is that the app is paused as soon as it goes into the background, you can delay this by 30 seconds, but if you take longer, the app is stopped and no more code is executed. Now I have found a...

www.b4x.com