In my app, I open a connection to use the iPad as a tiny FTP Server, then when the app runs, I can access to the app Documents with FileZilla, web browser, etc...
But can I keep this connection opened whe the app enter in background? I tried "Background Modes" but it doesn't work.
Thanks you all :)
EDIT : I use files from this project : https://github.com/sosoyososo/XZCodeBrowser
The background modes in iOS are limited. iOS devices are not designed to operate in the same way as a traditional computer, with multiple long-running tasks. There are various background modes available, as you have investigated, that can help applications perform tasks in the background, but these are more focussed on the user experience (e.g. allowing an app to periodically fetch data or receive location updates) than running "servers".
Apps in the background are managed to reduce demand for memory and maximise battery life, so they can be unloaded at any time.
The VoIP background mode allows iOS to keep listening for network traffic on your app's behalf and re-launch your app in the background if necessary, but if you use this for a non-VoIP app I believe you will have problems with app approval.
Related
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'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.
I'm new to mobile development, before eventually deciding where to develop (android/ iOS) a specific application I have a question (I'd prefer using an iPhone):
So the background is that I have a BLE device frequently sending data to the phone and let the phone app sync the data to the cloud. Now, it is really important that if for some reason the phone has to restart, it will automatically proceed receiving the BLE data.
Is it possible at all in iOS to start a background process (handling BLE packets) after reboot automatically. Thus e.g. when the respective BLE device pairs to the phone after a reboot, that the background process starts automatically, without the user having to start the app manually?
Doing some research I came up with mixed results regarding this scenario and would be grateful if someone with iOS experience could clarify.
(BTW: It does not have to be an Apple App Store Application)
A Few days ago I was working on BLE devices Beacons we supposed to make mobile application and start monitoring these beacons and send date monitoring to API.
This works fine in background, even the user was not running the application in foreground or reboot his iPhone.
All we should do is put the monitoring code at the appDelegate of the application to work in the background.
In ios, it supports long running background task for certain types of apps with background modes such as App registers for location updates,App provides Voice over IP services,App plays audio,App processes Newsstand Kit downloads,App communicates using CoreBluetooth,App shares data using CoreBluetooth.
My application in ios will updload file to remote server periodically if network connection exists.It will do this process if the file is available in the particular directory.
I want to know that in which mode above my app does come under?
the background modes are very restrictive and your app doesnt fit in any category. if you want to use background downloading, try the following tutorial:
iOS 7 SDK: Background Transfer Service
I am developing an iOS application that communicates with a slave BLE device. I know iOS will allow my app to run in background to communicate with BLE. What my doubt is that is there any way to turn on my app if there is any BLE near by? I mean even if my app is not running can I communicate with BLE? Like location service works,i.e., if the app registered for a significant location change alert then app will get automatically turned on when there is a significant location change even if app is not running.
I have searched a lot, but couldn't find any helpful documentation. Any help is greatly appreciated..
There are a few things here and I think you have to be careful with terminology. Let's first clarify "Not running". The app has 5 modes it can be in:
Foreground: the app is "live" and on the screen
Background - unlocked: the app is "live" but not on the screen. There is either another app on the screen (front) or possibly the user is on the home screen, browsing his/her apps, etc..
Background - locked: self explanatory
Terminated by user - still on device: The user has double clicked the home button and flicked your app up (iOS7) to close it.
Terminated by system - still on device: The app has been terminated by OS because of memory pressure (other apps needed the memory space).
Obviously, if the user has deleted the app from the device then there is nothing to discuss.
In option 4, the app is still on the device but will not relaunch any of its background services (BLE, location updates, etc..) until the user relaunches the app. This is new iOS7 behavior. If the user terminated the app then he/she does not want it running.
In option 5, because the user has not terminated the app; the OS will relaunch the app background services as it receives callbacks.
In order for an app to run in the background, it requires that you add the appropriate background modes to its plist or simply click on project (top left) and go to "Capabilities" and enable "Background modes" and the appropriate background mode. In your case: "Uses Bluetooth LE Accessories".
Now you seem to be looking for "Scanning" versus connecting and exchanging data and in my experience, scanning will only work in scenarios 1 and 2 and 5. Not 3. I have tried many times to get scanning to happen while phone is locked with no luck.
Now the way, fitbit etc... work in the background is that the app, scans, discovers services and characteristics and "setup updates" between the phone and accessory while the app is in the foreground. Once this setup is done, the "value of interest" updates (heart beat, etc..) can happen between the BLE acessory and the iOS device, in the background (locked and unlocked).
Hope this helps.