I am trying to create a GPS location app that will monitor and send the location to a server. I want the location service to be able to continue to run even after the app is terminated/killed(not just in the background).
Does anyone have any idea on how to do this?
You can do this, but your options are very limited
Your app won't be able to be in the store:
2.8 Apps that install or launch other executable code will be rejected
https://developer.apple.com/appstore/resources/approval/guidelines.html
It might get kill on background
Save user data and app state information. All unsaved changes should be written to disk when entering the background. This step is necessary because your app might be quietly killed while in the background for any number of reasons. You can perform this operation from a background thread as needed.
http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html
But if you still want to do this, check this out:
I guess the answer is 'sort of'. If you don't want to jailbreak phones, your options are rather limited. As long as you're only intending to distribute internally, you can look into the VOIP background services.
It's part of iOS 4's background services, and is intended to allow VOIP apps to run constantly in the background to pick up events such as incoming calls, etc. It is possible to use it to achieve other things, such as a regularly scheduled service (I think there was a recent question where somebody wanted to use it to act as a 'data counter', again for the enterprise program).
From Here: iphone daemon process
Related
I have been investigating iOS background fetch for our enterprise applications. According to articles like this, there are limitations like having 30 seconds to download before the app is terminated and the may be (unconfirmed) a penalty where after 3 timeouts, an app gets banned from background sync. Also if the user kills the app, fetches stop happening -noted here.
The goal is to be able to retrieve data from our servers periodically when app is suspended/not running but sometimes the transfers can take minutes due to long running SQL. I don't want to implement sending periodic notifications to all users.
Before I go down the path of developing for the iOS background sync, I needed to do some due diligence and research alternatives to iOS's background sync and didn't find anything.
Has anyone seen or developed an alternative to iOS's background sync or dealt with this issue for their enterprise apps?
As an enterprise app there's nothing extra you can do except that you can use whatever background modes you want (audio, location, voip etc,) without needing to have a legitimate reason to do so.
Where this might assist is:
you could make use of a significant location change (as opposed to a regular location change) notification to run your app in the background. The problem with this is it of course depends on the user of your app to move around. However, assuming everybody in your workforce commutes to/from work with their iPhone then you would have two opportunities each day for the app to run in the background. A app run due to a location change can be made to execute in the background for more than 30 seconds.
voip pushes: Unlike a regular push notification, a voip push will launch the app even if the user has force terminated it. To make use of this functionality is only a tiny bit more effort than using regular push, you don't have to do anything regarding making or receiving an actual voip call, you just need the voip capability and voip certificates instead of normal push certificates.
The comment in that link is not correct regarding force quitting and background fetch - a user force quitting an app does not make it ineligible to run for a background fetch, I have force quit my own app that uses background fetch but it will still be started by the OS, however what will happen is that the frequency when the app is run will decrease lots, and if the user never runs the app again then the OS will stop launching it.
A user force quitting an app will prevent other things from happening, such as it running in the background in response to a silent push notification for example (unless its a voip push).
Also the 30 seconds in not related to download times, NSURLConnection would stop after 30 seconds, NSURLSession is designed to continue to download on your app's behalf. But if you are downloading and then applying lengthy SQL processing it would be an issue. But minutes of processing time seems excessive, are you sure its all optimized?
The goal is to be able to retrieve data from our servers periodically when app is suspended/not running
The only reliable way to achieve such a behaviour is implementing a User-facing Remote (Push) Notifications framework on backend & apps.
You can append 4kB (or 5 for VOIP) worth of data in the push JSON payload, eliminating need for a network fetch request if implemented in a handshake mechanism.
You can evaluate usage on Silent Remote Notifications to augment content updation & fetch small amounts of content opportunistically, though it has the same as Background App Refresh.
You can definitely improve the API that can take minutes due to long running SQL
And remember you need to have the app updated only when the user actually fires it up. Evaluate implementing a catchy & smooth fetching content screen that transitions into the actual screens once all data is fetched.
I want my iOS apps to run continuously in background 24/7
I tried many options like background location updated with background task expiration handler, but later after some times it seems that the application gets suspended in background and user is brought back to the root view controller.
Any help will be appreciated.
For tasks that require more execution time to implement, you must request specific permissions to run them in the background without their being suspended. In iOS, only specific app types are allowed to run in the background:
Apps that play audible content to the user while in the background, such as a music player app
Apps that record audio content while in the background
Ap ps that keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Apps that need to download and process new content regularly
Apps that receive regular updates from external accessories
Apps that implement these services must declare the services they support and use system frameworks to implement the relevant aspects of those services.
Declaring the services lets the system know which services you use, but in some cases it is the system frameworks that actually prevent your application from being suspended.
You should read this page of Apple Programming Guide : Background Execution
It is not allowed to run background tasks 24/7. But you can use many different ways.
You simply can't. Apple don't give any mean for an app to ensure background execution. iOS will give you processing time whenever it feel like it, and you cannot control that.
I have always coded for Android, and now I'm looking to expand my knowledge to iOS development; so I'm really new at this, please be patient.
I understand that only a small group of apps are allowed to run indefinitely in the background. Those are VoIP, Music players and location tracking apps.
I want to write a chat app using the XMPP framework. Everything is fine until the user puts the app in the background, in which case, the app will stay connected for about ten minutes to then be killed by the system and therefore the user won't be able to receive new messages.
I am aware of hacks to keep the app alive. Hacks such as defining it as a music playing app in the info.plist file and then just play some empty sound indefinitely. But I'm also aware that Apple will reject the app when it's time to publish to the App Store.
So, normally, how do other apps do it? How can other chat apps stay alive in the background to receive new messages from the servers? Apps like Google Hangouts, IM+ and such?
Ideally, they aren't really running in the background, but use push notifications, as others have mentioned.
But some chat clients seem to do something else: I've verified (by sniffing the traffic of an idle iOS device) that at least Google Hangouts, Facebook and Skype all keep a persistent socket opened in the background, and regularly send traffic to keep it alive.
I'm suspecting that they are using the VoIP exceptions to Apple's otherwise strict background execution policies. iOS allows "VoIP apps" to run in the background and keep one socket open to be notified about incoming calls and messages.
Maybe they are also using the new "background fetch" feature of iOS 7, but as far as I know, that doesn't allow persistent socket connections.
The iOS operating system allows for the existence of something called a PUSH NOTIFICATION
There exists hundreds of tutorials online which teach you how to implement the notification code and how to respond accordingly when you receive such a message!
http://www.raywenderlich.com/32960/apple-push-notification-services-in-ios-6-tutorial-part-1
Check this link out for an in-depth tutorial on push notifications!
http://maniacdev.com/2011/05/tutorial-ios-push-notification-services-for-beginners
I think most of these apps use push notifications and just load the last messages from the server as soon as the app is being opened.
While there are some hacks, and your app can ask for more time when it goes in background (up to a point, and with no guarantees), this is a perfect application for push notifications.
The server tells the phone there's a message, and iOS wakes your app up to process it.
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Introduction.html
As of iOS 7 there is a new background-execution mode - 'fetch' for apps that need to periodically fetch new data. It sounds like your case would meet that definition.
You can find the information in the iOS App Programming Guide -
Fetching Small Amounts of Content Regularly
In iOS 7 and later, an app that retrieves content regularly from the
network can ask the system for background execution time to check for
new content. You enable support for background fetches 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 fetch value in your app’s Info.plist
file.) At appropriate times, the system gives background execution
time to the apps that support this background mode, launching the app
directly into the background if needed. The app object calls the
application:performFetchWithCompletionHandler: method of its app
delegate to let you know when execution time is available.
You can also use push notifications, but that requires some server infrastructure
An app running in the background has limited capability. Read App States and Multitasking thoroughly to decide how best to design your app. Chat is not listed as one of the specific exceptions that can operate with a more relaxed policy. You will never be able to "keep [your] app live in background forever." You might be able to leverage an iOS 7 feature also described in this guide, Fetching Small Amounts of Content Regularly.
iOS App Programming Guide: App States and Multitasking
https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOS ProgrammingGuide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html
I know that iOS has its own task management method and users may never need to care about the processes background. But my requirement is to ALWAYS keep a program alive, it cannot be killed under any circumstance.
Is there a way to do this like "LOCK" or something else function already existed? I'm using iPad4 ios6.01 system.
Thanks
No, that's not possible. (Nor should it be if you think about it. What's to stop every app from saying that it can't be killed?)
The closest you can get is for things like VoIP apps that do run in the background and automatically respawn when they die.
The alternative is to work like every other app: when your app goes into the background you save state so you can restore if it gets killed. iOS 6 even has the state restoration functions.
Short and simple
No, there is no way to make your App "unkillable".
A bit longer
If your App requires to receive location updates while it is running in background, you can use the standard way Apple offers to do so.
Two other options are: your App is an VoIP application (afaik they also get autostarted on system boot) or you're playing audio in the background. Without knowing too much details about how iOS handles such Apps, they might get killed if the iDevice runs out of memory (or the user kills it). But you probably already knew that.
However, as you already mentioned, iOS manages everything on it's own and will kill Apps that run in background to free memory. Additionally as we all know, a user might kill your App at any time using the task switcher of iOS.
And don't try to use the described methods just to run tasks in the background. If Apple finds out about it, your App will be rejected/removed from the App Store quickly.
I'm spec-ing an iOS app (which will be built outside of our company) which will upload a user's data entry to a server. If the device is not connected to the Internet, we'd like to save data on the device and upload it when the network is re-connected. (The app will primarily run on iPod Touch devices that will be disconnected most of the time).
If the user unlocks the device and re-opens our app after the network is reconnected, then uploading to the server should be easy because the app is running.
But what if the app is not running, where "not running" can mean one or more of:
device was power cycled
user has locked the device and it's sitting in his pocket
app crashed
user exited the app
user started using other apps so our app isn't running in the foreground anymore
are there other cases?
In the cases above, is there a way (ideally a battery-efficient way) to ensure that local data is uploaded soon after Internet connectivity is restored? Is the answer different depending on which of the cases above caused the app not to be running?
And is there a minimum iOS version the device will need in order to enable some (or all) of the above not-running cases to still upload when the app is not running?
My apologies if these are obvious newbie questions-- I'm not an iOS expert.
There is an interesting technique that is used by among others Instapaper and News.me(the pioneers of this technique) where you use region monitoring to initiate background downloads or uploads. Marco (Instapaper) blogged and talked (in episode 80 of the Build and Analyze podcast) about his communication with Apple so it should be a allowed in the App Store.
In brief the technique is that you set up certain regions (geofences) like "home" or "work" and respond to the locationManager:didEnterRegion: (and similar) callback(s). Your app will wake up from the background once you enter the pre-specified region and you can check to see if there is any data to upload.
This technique won't guarantee that the data is uploaded when the network reconnects but it will allow your app to automatically upload the information when the iPod Touch users gets home to their WiFi network.
That should most likely be at least once a day which may or may not be frequent enough for you. You could add a timestamp to when the initial upload was attempted and send that along the upload once it succeeds to get the correct order of events (data entries) on your server.
There is no way to ensure this. If your application is "not running" (by the definition described in your question), it will not be capable of responding to a change in the device's network status. It should be setup to resume upload operations the next time the application runs again.
EDIT:
Some of the cases you've described may indeed provide different opportunities for your application. Specifically, if the user "exits" the app by pressing the home button or launches another app in the foreground, your application may continue to run the in the background and could potentially respond to a change in network reachability.
The nature of what may be done in the background and for how-long is well documented, and supported by any version of iOS that supports multi-tasking. I recommend you review the documentation pertaining to App States and Background Services.
device was power cycled --> really NO WAY of resuming, unless you open the App!!!
user has locked the device and it's sitting in his pocket --> apps applicationStatus is UIApplicationStateInactive but it is running in the background. You still are able to react to notifications and i.e. accelerometer events. Try the Reachability Class and Log the changes!
app crashed --> NO WAY, unless opening the App
user exited the app --> App is sitting in the background. There you have a maximum of 10 Minutes Restriction of fully using your App (like the App "Pastebot" does)
user started using other apps so our app isn't running in the
foreground anymore --> Same as user exited the app
On multitasking Apple says the following:
Real multitasking only for certain kinds of usage, as there is Audio Background playing, VOIP (like Skype), navigation applications
All the other apps can request a specific amount of time after the app is closed/in the background, to finish certain tasks (as sending an email, sms or uploading/downloading important data)
Important Quote from dev docs:
Your app delegate’s applicationDidEnterBackground: method has approximately 5 seconds to finish any tasks and return. In practice, this method should return as quickly as possible. If the method does not return before time runs out, your app is killed and purged from memory. If you still need more time to perform tasks, call the beginBackgroundTaskWithExpirationHandler: method to request background execution time and then start any long-running tasks in a secondary thread. Regardless of whether you start any background tasks, the applicationDidEnterBackground: method must still exit within 5 seconds.
If you're building a restful API then I would recommend using RestKit, it has a request queue that checks the network status on the device and starts uploading once network access has been assured. You can read more about this here: http://mobile.tutsplus.com/tutorials/iphone/advanced-restkit-development_iphone-sdk/. Read the sections about Request Queue and background download/upload. It should be noted that RestKit is a big library which has it's advantages and disadvantages. I'm not completely sure how this que works with the app lifecycle, if it saves the request que even if the app is terminated. You would have to investigate that. RestKit does support background uploading/downloading, but as already noted, I think it's impossible to do any uploading if the app is terminated and not in background state.
I wouldn't recommend using RestKit if the API isn't Rest though.
You can download and experiment with RestKit here: https://github.com/RestKit/RestKit.