I am writing update checker program in xcode, my program needs background process( it needs to be run in background), so is it possible in phonegap, and is there any phonegap plugin for background services? Thanks
iOS does not allow background task to run more than a specific time limit.
Similar Post:
iPhone background task stops running at some point
Explanation:
http://www.macworld.com/article/1164616/how_ios_multitasking_really_works.html
The reasonable solution would be to implement a push notification and send a notification whenever there is an update on server.
It is definitely possible to run some JS code in the background to be checking this (https://github.com/jocull/phonegap-backgroundjs).
It won't be possible to do it for more than 10 minutes in the background, though (Run app for more than 10 minutes in background)
So you'll need both a combination of the first plugin I mentioned and the PN service that dhaval is suggesting.
Cheers!
Related
I am trying to create a flutter app that sends notification every time there is new entry in stream builder, it works fine when the app is on or opened but I want it to work and receive notification even when it is not opened , I have used workmanager to make the task work in background but it is not working ...the code for it can be found here code
Flutter apps by nature are supposed to run on a UI thread or foreground. The background tasks you are asking for are features disclosed by each individual platforms.
In case of Android, you can create a a Background Service to accomplish the tasks you need to perform when application is closed. The link to the bacground service is as follows: Creating a Background Service
In case of iOS, see this link for creating a background task. Other platform implementation will be as like above, so please have a look into each platform specific background process.
UPDATE:
Please have a look into the package Flutter Background Service. This package helps to deal with background tasks setup from flutter side even when app is closed.
NOTE:
Q: Why the service not started automatically?
A: Some android device manufacturers have a custom android os for example MIUI from Xiaomi. You have to deal with that policy.
Q: Service killed by system and not respawn?
A: Try to disable battery optimization for your app.
As per the latest update of Kindle V2.5, it has support of "continue downloading books while the app is in the background on iOS 4 devices".
How is it possible to download content in background? As per the iOS multitasking documentation, only audio, voip & location updates are possible in background. And I've also maken sure that NSURLConnection doesn't download new data work while app goes background. Then how's it possible with Kindle app?
Edit: I haven't checked Kindle App in iOS4 multitasking enabled device. So if anyone let me (& community) know what exactly Kindle app does to download, that would be very much helpful.
Yes you can. Go back to the document you mentioned, and check the code at the Completing a Finite Length Task in the Background section. In this way you can run generic tasks in the background, including accessing the network and uploading files.
Edited: I answered a similar question on SO before, check this, iphone - Connecting to server in background
Completing a Finite Length Task in the Background
You can use these methods to do pretty much anything you want, but you've got to finish it all up in <10 minutes. I use it to continue uploading an image after the app has closed.
I am actually doing some daily checks of the app assuming the app will be closed and opened daily. It works fine for 3.1 devices. My question is how many days can a app live in background on iPhone 4.0 OS.
If it lives for a long time what are the best ways to make daily schedules to contact my backend server ?
Backgrounding in iOS4 is more restrict than that. You can schedule 'task completion' but that can only run for 10 minutes. You could possibly do the 'location' background service but that would use quite a bit of power and I'm not sure if it would let you contact your server like you are talking about.
I suppose a more direct answer to your question is that it depends. When you are in the background, you need to be prepared to have you app closed at anytime. When the device runs low on memory, it will close any app that hasn't be run in a while.
Apple's Doc on Background Tasks
Why do you say it works fine for 3.1 devices? If you want the app to update when opened from the springboard like it does in 3.1 then you want to use applicationWillEnterForeground: in your app delegate to call the right code.
If you must update periodically in the background then you can use setKeepAliveTimeout:handler: and beginBackgroundTaskWithExpirationHandler, but I don't know what the app store reviewers will think about a non-VOIP app using using it.
In my iPhone app I would like to run several queries when the
application is in background.
I already use ASIHttpRequest to make the queries, that works fine but
now I try to find a way to trigger them in background.
In the app delegate, I have added a call to the method making the request:
[self getItemsFromServer]
getItemsFromServer runs an asynchronous request (on the simulator I
saw the log of this methods once I get back the application to the
foreground).
How can I use some kind of timer to have this method ran every 10
minutes (I just need to run it 4 or 5 times, not each 10 minutes until
it goes back to foreground :-) )?
thanks a lot,
Best Regards,
Luc
iOS4 allows your app to run for X amount of time, granted that iOS4 grants you the time you request. Check out: Completing a Long-Running Task in the Background.
Specifically,
Any time before it is suspended, an application can call the beginBackgroundTaskWithExpirationHandler: method to ask the system for extra time to complete some long-running task in the background. If the request is granted, and if the application goes into the background while the task is in progress, the system lets the application run for an additional amount of time instead of suspending it
You could probably use Task Finishing to do that. In iOS you can mark a thread as finishing and give it a specific time to live. This would let you do a few more calls to your web server.
Have a look at Executing Code in the Background
Actually, you are specially not allowed to make general HTTP calls while in background. The only apps that can be active in the background are those that play audio, do location or are running VOIP calls. I believe Apple's whole philosophy with background is that apps shouldn't be doing 'work' other than these limited cases because there are limited resources available. THe suggested way to work around this is to use (ugh) notifications or just do a refresh when your application wakes up. The doc that willcodejavaforfood references explains this.
Ever since the first beta came out I’ve been trying to find out if “real” multitasking is possible — i.e. can you put a program in the background and have it hang on to a network connection indefinitely?
I’m thinking about IM or IRC apps, for example. I’ve compiled an app myself on iOS 4, and without changing a thing it appeared to stay running in the background, but for all I know it was just suspended to memory.
The docs say the best you can do is request up to 10 minutes, but in the developer presentation they showed off Skype sitting in the background and then notifying the user that a call was coming in. Does anyone know for sure how this all works?
It appears the answer is no. The API for Skype is a very special case, called the "voip" mode, and requires special behavior, such as marking the socket in use for VoIP.
You can receive alarm notifications in the background (such as time passed). The amount of time you are in the background running state is severely limited by the OS.
Android's background model is complete and in many ways much nicer.
Apple has a guide named "Supporting Multitasking In Your Applications" which you should be able to locate.
Apple's iOS 4 developer docs outline this all very clearly.
When your app is closed or switched away from, it is almost immediately "suspended", meaning the OS freezes the app's state. When the user switches back to your app, your code keeps running just where it kept off. You don't need to add any code to your app to do this, just compile it against OS 4.
The above is true in most cases. There are two reasons the "suspended" model may not apply:
1) If the device starts to run low on memory, the OS will start terminating suspended apps that haven't been switched to in a while, without warning. This is why it's in your best interest for your app to remember it's state as well, so if your app is terminated, then re-opened, the user doesn't really notice because it still returns to right where they left off.
2) Your app uses one of the "background" APIs. These are for audio playback, VoIP services, or location services. In this case, your app is allowed to continue running in the background but only has access to those APIs. Additionally, your app can designate certain long-running tasks as "background tasks" that need to be completed before the app is suspended or terminated, like uploading pictures to Flickr or rendering a video, etc.
The "background task" method doesn't cover pinging servers indefinitely, as there is a time limit for the task, after which it will be forcibly halted. Apps that need that sort of functionality are expected to implement push notifications, just as before.
That should clear this up. All in all I think it's a pretty elegant solution to multitasking on a mobile device.
iOS 4 applications can either be running or suspended. The operating system will try to keep as many requested applications as possible in memory, while all other applications are suspended.
Applications that run in the background can access features such as navigation, audio, and VOIP (but NOT instant messaging). So it looks like you might be out of luck.
-- PC World Multitasking on Apples iPhone 4
It is possible for apps to request background time. Read the docs. I would say it iOS is "controlled multitasking".
You can create a long running background task, I believe these can include networking features. Just have to set the background task flag on the work block.
https://developer.apple.com/iphone/library/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html
the OS can limit exactly how much time you get though... it will tell you when your time is up giving you a chance to cleanup nicely.
iOS 4 has "real" multitasking to some extend. There are two things to consider:
The UI event loop is single tasking. So only the front app executes on the UI event loop. Not a big deal: detach your main code form the UI event loop (maybe you need to redesign your app).
The OS "may" terminate your app if some criteria are met (e.g. low memory).
Currently one of these criteria is that execution time is limited to 10 minutes (real time not cpu time). However I expect this to change and see better criteria for background app termination (I hope to).
Apart from this you can have timers (event loops) in background.
There is no real multitasking in iOS 4.2 even. because apps will only be allowed to finish the task related to states..for small interval of time and then it will be in suspended state.. If you will set background task for long interval of time then... it will behave unexpectedly like no method will be called when you will try to run the app from anywhere..
You may be interested in this blog post that outlines how "multitasking" works in systems such as iPhone OS 4 and Android.
in fact u can do this, although it's not allowed by Apple. u gotta set up a toolchain in ur mac and use some unofficial SDK...
check http://code.google.com/p/iphone-backgrounder/ for more information
You should use the Push Notifications framework for the feature set you are creating!