It seems like older versions of iOS allowed your app to run for 10 minutes in the background. Now it seems like iOS only allows your app to run for a maximum of 3 minutes. I haven't found any documentation mentioning when, or in which versions, this changed, or any estimates provided by Apple for how long your app can run in the background.
I need to be able to run in the background, because my app is connected to an external device via TCP. I already know about the hacks you can do with VOIP and playing silent audio (both will get your app rejected).
Is there anything I can do to get my app to keep running in the background longer than 3 minutes?
We haven’t had the old 10 minute window for years so that is simply no longer applicable. That was reduced to 3 minutes in OS 7, and further reduced to 30 seconds in iOS 13. (There is a new concept of background tasks, for running tasks longer than 30 seconds, but the the OS will run these at its own discretion, e.g. at night, when the user is charging their device, so that’s not really applicable here).
The short answer to your question is that you cannot submit apps to the store that run in the background indefinitely unless it’s one of a very limited list of permitted background modes.
If you can go to the “Signing & Capabilities” tab of your target and add “Background Modes” and you can see the list of alternatives:
So, with the caveat that you cannot do precisely what you asked, here are a few observations:
The “External accessory communication” background mode (see ExternalAccessory) seems promising, but that’s for bluetooth or wired connections only. So unless you can refactor/reengineer how your devices communicates, that is likely not a viable solution.
There’s an interesting question of whether just keeping the app running in the foreground might be helpful (e.g. judicious use of idleTimerDisabled). I know this solves a different problem (and should be used only where essential), but perhaps it’s option for you.
If your external device is Internet-enabled and you want it to inform the app of some event, perhaps you can have it communicate its intent to some web service that then triggers an APNS push notification that your device can receive.
Bottom line, you can’t do what you ask, but if you edit your question with more details about the nature of the device and what your iOS app wants to do with that device, we might be able to provide better counsel. But in answer to the general question “can I just keep app running perpetually in the background”, the answer is “no.”
Related
I understand that this issue has already been covered extensively in the past, but I'd like to readdress it it appears that there is a lot of mixed messaging around the subject.
I have an application that should be periodically updated, roughly once a day at the minimum, to run some maintenance tasks. I have researched extensively on how to achieve this behaviour, but options such as background fetch and silent push notifications do not appear to work when the app has been terminated (swiped up on) by the user. (see this link for app states)
Will IOS wake up my app if it is in the terminated state, for example, if a user has swiped up on the app? I would like to find a solution that allows me to have the app run in the background in as many circumstances as possible.
What are my options here?
It is not possible to run a terminated app with Swift. Once an app has been terminated, it is no longer running and cannot be restarted. The only way to run the app again is to open it from the device's home screen or app launcher.
Suppose I am using one App (no other App is active). Now I lock the iPad by simply clicking the lock button or may be I put it in background mode and put my iPad somewhere.
After what amount of time, the App will get killed automatically by system if I don't use that App? Is there any specification by Apple or we cannot say anything that App will launch from scratch in some scenarios.
Note that in any scenario, I don't kill my App manually.
iOS generally (at least in current versions) doesn't kill apps after some arbitrary time. It kills them when it needs to free up resources. Since modern iPads have quite a bit of memory, that means that apps can stay in the background for a very long time depending on how the iPad is used. As Andreas notes, however, there are no promises about that.
I have a Timer which plays AVAudio at a specific time while the screen is locked (app in foreground when locked and plist setting 'Application does not run in background' set to YES).
When I run my code while my iPhone is connected to Xcode it works as desired, playing audio while locked even when the iPhone has been locked for hours.
Now if I disconnect my iPhone and just open the app by tapping the icon the audio won't be played if it's set for more than a minute.
Is there a difference that causes this problem? If I would publish my App to the AppStore which behaviour would my users get?
That 'Application does not run in background' flag is a very old flag that means your app does not support multitasking and should be terminated when the user presses the home button. There's no good reason I can think of to set that flag on a newly developed application. Unless you understand exactly what it's for and are positive that setting it to yes is the correct thing to do, don't do that.
(That flag was added when iOS 4 was released, to allow apps that could not handle multi-tasking to request the old terminate-on-home-button behavior from iOS 3. Given that we're now 6 major iOS releases from iOS 4, it seems outdated.)
So remove that flag. It probably doesn't have any impact on your question, but remove it or set it to no in any case.
If you want to run a timer while the phone is locked and play sounds at designated times then you will probably need to set your app up as a background sound player, and ask for more background time when you get a message that you are going to the background.
That being said it's likely that Apple will reject your app. Running a timer from the background means that the processor on the phone has to run at full speed all the time, which will DRAMATICALLY reduce battery life.
Apple only allows a very small subset of apps to run in the background, and then only under specific circumstances (like a background sound playing app when the user is actively listening to music, or a navigation app that is actively tracking the user's location and notifying them when it's time to make a turn to follow directions.)
Should be no different. If you'd like to feel what do your users' feel then you can publish it to TestFlight which is the best app beta test environment. Find some testers or try it yourself.
The directions should be to verify the playing logic and the sound file relationship which link to the connection.
I'm trying to develop a little app in order to learn coding for iOS. The app needs to check the battery level every minute and accordingly send an HTTP request. This works when the app is awake.
How can I make it run when the device is put in sleep mode?
The short answer is you can't, or at least shouldn't.
Apple doesn't allow apps to run in the background for extended periods of time with a few exceptions like navigation apps, VoIP apps and a few others (a full list can be found here).
I recommend that you read about UIBackgroundModes and the app lifecycle in the link I attached.
Happy coding!
This is a strange one, I have a need to create an iOS app that runs in the background on an iOS device, but can not be visible on the Home screen of the device. The app may need to show up in Settings to configure a few options, but it mostly needs to run behind the scenes.
I do not need to publish this app on the app store, it is strictly an enterprise app for my company.
Does anyone know how this kind of behavior might be achieved? Configuration profiles? API's? etc?
Edit: Jailbreaking the device is not really an option for us. We have to keep the devices as they are.
Backgrounding
There are several methods to get permanent background execution:
a) Silent audio which is mentioned by JRG-Developer
b) Usage of beginBackgroundTaskWithExpirationHandler + turning location manager on/off (it will reset remaining time to 600 seconds)
Making app invisible
You can use SBAppTags in Info.plist (take a look at this: How to remove app icon programatically from jail broken iPhone app?)
It will make your icon not visible on Home screen.
I've no idea how you can tackle the not be visible on the home screen criteria, but there are certain services that are allowed to be run in the background continuously, notably:
Background Audio (even silent audio)
While this is indeed very hacky, short of jailbreaking the devices, this may be your best bet.
While it's unlikely / very difficult to get past the review process, in the event for some reason you do need to (attempt) to publish this app to the App Store, some apps are even available on the App Store which take advantage of this hack, such as PasteBot.
You should definitely read their write-up here about getting their app's Cut-and-Paste functionality to work while in the background:
http://tapbots.com/blog/pastebot/pastebot-music-in-background
Another out-of-the-box idea, why not use Android devices instead, which do support multitasking?
Two methods:
Jailbreak. A jailbroken iPhone is essentially a Mac and you can use all Mac UNIX programming tricks - spawn a daemon (you can even ask launchd to do that), or something. You can set up enteprise-wise Cydia source. Refer to saurik's website for a walkthrough and set up an experimental server using Ubuntu (which used apt too)
A non-jailbreak way may be possible, but it will depend on what your app is doing. You can try use enterprise-wise push notifications.
Given that this is impossible to do on non jailbroken phones, I'd suggest the following:
develop a directory app, or a phone list app, something that is specific to your company.
have it connect to a web service once a day to register the device ID (so you know the user has not deleted the app)
tell users they need to keep the app open at all times (and if a user's device does not register one day, send them an email asking them to launch the app).
Now you can send back whatever you want with the app. If they kill it, you'll know the next day when you have a script look at the logs.
If you think this is a terrible idea, it is, but its the best you are going to get on iOS right now.
EDIT: you could send a notification every day - say in the AM - to make sure the user opened the app if it wasn't running.
From my experince, this kind of behaviour cannot be achieved on iOS. When an app enters into background, it is active only for a small particular amount of time. After that, it goes into hybernate state. It stops working. So the behaviour you said can not be achieved without abusing iOS workflow. Thats why some call iOS's multitasking as not true multitasking. Only jailbreaking might help your case. That was for one case. The second one where the app cannot be seen on home screen is again, impossible. It has to be on springboard to run.