I'm afraid I already know the answer of my own question, but I decided to ask anyway before losing my hopes.
I have the following use case: an app writes some bytes in a "shared" resource (let's say on a file) and another app reads the data and sends them to an external device via BLE while in background. Unfortunately, I know that concepts like shared resource and background are bounded in iOS. What I tried so far is:
Using App Group to share data between two apps
This is working fine even in background, but both the apps need to be produced by the same developer team (i.e. Team ID must be the same). This is a problem because one app is not produced by my developer team.
Copying data in the pasteboard
This is not working when app is in background. Data will always be nil and will update only when the app becomes active again.
...and of course there are...
Background limitations
Even though I go for the App Group solution, the only way I can manage to read data and send to the BLE device in background is by starting a background task. This obviously is a caveat: the task has an expiration time (from tests I performed it keeps going for about 3 minutes before being suspended by the OS). I don't need to run a long-time task, but I cannot assure it can be performed completely by 3 minutes or so.
Here's the question: Is there some other solution for this use case or should I finally give up?
If you are using CoreBluetooth to send files to your Bluetooth device, you can try adding bluetooth-central as UIBackgroundMode key in Info.plist of your app.
Apple has mentioned this in its programming guide:
Communicating with a Bluetooth Accessory Apps that work with Bluetooth
peripherals can ask to be woken up if the peripheral delivers an
update when the app is suspended. This support is important for
Bluetooth-LE accessories that deliver data at regular intervals, such
as a Bluetooth heart rate belt. You enable support for using bluetooth
accessories from the Background modes section of the Capabilities tab
in your Xcode project. (You can also enable this support by including
the UIBackgroundModes key with the bluetooth-central value in your
app’s Info.plist file.) When you enable this mode, the Core Bluetooth
framework keeps open any active sessions for the corresponding
peripheral. In addition, new data arriving from the peripheral causes
the system to wake up the app so that it can process the data. The
system also wakes up the app to process accessory connection and
disconnection notifications.
In iOS 6, an app can also operate in peripheral mode with Bluetooth
accessories. To act as a Bluetooth accessory, you must enable support
for that mode from the Background modes section of the Capabilities
tab in your Xcode project. (You can also enable this support by
including the UIBackgroundModes key with the bluetooth-peripheral
value in your app’s Info.plist file.) Enabling this mode lets the Core
Bluetooth framework wake the app up briefly in the background so that
it can handle accessory-related requests. Apps woken up for these
events should process them and return as quickly as possible so that
the app can be suspended again.
Related
My Problem: I have an app that communicates with a medical BLE device. I have it all working but my problem is that when an ios user puts the app in the background I stop getting/processing the messages sent via bluetooth. Android seems to keep getting these messages but from what I've found, on iOS, the JS bridge is torn down and there isn't a solution out there for this problem. The phone must continue to process the data sent from the BLE device.
My thought is this and this is my question for you all.
Would it be possible to create a native module for ios that will always be running and be doing the following: getting ble data as it is notified. Store that data to the file system and push it to a webservice all while the app is in the background? It would also be great to have the ability to read the fs created files and show some data about them when the app comes back to the foreground. Would this be possible?
Do you know of another option that could work?
Any help is greatly appreciated.
OK as I was heading down the native path and reading on the ios bluetooth schtuff I found this article Core Bluetooth Programming Guide and specifically it mentions a plist setting.
The Core Bluetooth background execution modes are declared by adding the UIBackgroundModes key to your Info.plist file and setting the key’s value to an array containing one of the following strings:
bluetooth-central —The app communicates with Bluetooth low energy peripherals using the Core Bluetooth framework.
bluetooth-peripheral —The app shares data using the Core Bluetooth framework.
So I thought to myself, would just by adding these keys to my xcode project that iOS would be smart enough and not care that I am a RN app and not native... well that was the ticket! I plugged these values in and the ble data is processed even when I open another app. "Wallah!" ;)
You have to enable iOS background mode capability in your Xcode project settings.
Also take a look at react-native-ble-plx which provides background support for both iOS and Android.
in my app, I am connecting my app to BLE device. and I am fetching BLE data from BLE device at every 1 second. it working fine when I do this in the foreground.but I want to do same in the background even when the app will be in the background I need to fetch data continuously from BLE device. right now its stoped automatically after 2 minutes.
Please let me know if it's feasible or not?
Thanks in advance
You need to enable Background Mode in your project settings under capabilities tab. Under background modes you will find a few modes that satisfy various purposes of running an app in background. From these you have to enable the ones that you think are suitable according to the task that your app will perform in background. I think, you should enable external accessory communication and background fetch.
Also you need to implement a background task when your app enters background. This is done in app delegate's didEnterBackground method.
Apple documentation
Apps that work with Bluetooth peripherals can ask to be woken up if the peripheral delivers an update when the app is suspended. This support is important for Bluetooth-LE accessories that deliver data at regular intervals, such as a Bluetooth heart rate belt. You enable support for using bluetooth accessories from the Background modes section of the Capabilities tab in your Xcode project. (You can also enable this support by including the UIBackgroundModes key with the bluetooth-central value in your app’s Info.plist file.) When you enable this mode, the Core Bluetooth framework keeps open any active sessions for the corresponding peripheral. In addition, new data arriving from the peripheral causes the system to wake up the app so that it can process the data. The system also wakes up the app to process accessory connection and disconnection notifications.
In iOS 6, an app can also operate in peripheral mode with Bluetooth accessories. To act as a Bluetooth accessory, you must enable support for that mode from the Background modes section of the Capabilities tab in your Xcode project. (You can also enable this support by including the UIBackgroundModes key with the bluetooth-peripheral value in your app’s Info.plist file.) Enabling this mode lets the Core Bluetooth framework wake the app up briefly in the background so that it can handle accessory-related requests. Apps woken up for these events should process them and return as quickly as possible so that the app can be suspended again.
Any app that supports the background processing of Bluetooth data must be session-based and follow a few basic guidelines:
Apps must provide an interface that allows the user to start and stop the delivery of Bluetooth events. That interface should then open or close the session as appropriate.
Upon being woken up, the app has around 10 seconds to process the data. Ideally, it should process the data as fast as possible and allow itself to be suspended again. However, if more time is needed, the app can use the beginBackgroundTaskWithExpirationHandler: method to request additional time; it should do so only when absolutely necessary, though.
I want you to understand to my English skill is not good.
I'm developing an app using CoreBluetooth.
I checked I can do Bluetooth work in the background after running the app once (scanning, connect, get services).
However, I'm wondering if CoreBluetooth communication is possible in the background mode work without running the app at all.
For example, Once measurements are initiated on the peripherals, the central app will detect them and operate in background mode.
Is it possible?
I'm sorry that there is no code. Now I'm there is no method to start that.
I guess what you are looking for is CoreBluetooth State Preservation and Restoration. According to the documentation:
Because state preservation and restoration is built in to Core Bluetooth, your app can opt in to this feature to ask the system to preserve the state of your app’s central and peripheral managers and to continue performing certain Bluetooth-related tasks on their behalf, even when your app is no longer running.
When you opt in to state restoration, your app will be relaunched into the background on certain BLE related events. In particular, it keeps track of the following:
The services the central manager was scanning for (and any scan options specified when the scan started)
The peripherals the central manager was trying to connect to or had already connected to
The characteristics the central manager was subscribed to
Please be aware that there are limitations to what you can do while your app is using state restoration and background execution (you might be aware of that already).
Hope that helps
P.S.: We have found that state restoration only works while your iOS device is not attached to your development machine via USB cable (might be different with Xcode 9 now).
I have added "App communicates with an accessory” under the Key “Required background modes” in my apps info-plist so that when the app is killed in any way iOS will prompt the user to restart the background syncing for any connected BLE devices.
I have read lots of documentation and seen lots of comments however nothing concert I have only had one other person tell me if I use this our app it will not be accepted into the app store.
The external-accessory background mode is for MFi accessories, not BLE accessories. There are separate Core Bluetooth background mode entitlements for BLE (bluetooth-central and bluetooth-peripheral).
If you declare the MFi accessory background mode but your app does not connect to external MFi accessories then you can expect your app to be rejected.
This is covered by clause 2.16 of the App Store Review Guidelines
2.16 Multitasking Apps may only use background services for their intended purposes: VoIP, audio playback, location, task completion, local notifications, etc.
Is there a way to know when the device is rebooted in ios, like "BOOT_COMPLETED" permission in android. Went through internet and could not find and appropriate answer. Any help would be appreciated.
https://github.com/lithium3141/BootLaunch
You can refer this page but one think, if your app doesn't have voip feature means Apple will reject your application.
Apple State in their document:
https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/iPhoneOSKeys.html#//apple_ref/doc/uid/TP40009252-SW1
UIBackgroundModes
voip-The app provides Voice-over-IP services. Apps with this key are automatically launched after system boot so that the app can
reestablish VoIP services. Apps with this key are also allowed to play
background audio.
remote-notification-The app uses remote notifications as a signal that there is new content available for download. When a remote
notification arrives, the system launches or resumes the app in the
background and gives it a small amount of time to download the new
content.
This value is supported in iOS 7.0 and later.
voip key is the technique used most of the voip applications like skype.