I'm new to iOS development and I'm using Swift in my current project.
I'm trying to achieve something similar I did in Android. I'm trying to run a background service when the app is closed/minimised that will get executed every 2 seconds to keep the user informed that the app is still running in the background and checking for status with the server.
How can I achieve that? I've tried using the "background fetch" method but it doesn't get executed every 2 seconds.
The background service will run no longer than 5 minutes if it matters.
No you can't do that. What you can do is, call a service in applicationDidEnterBackground that lets your server know that your app is in background or killed(You will get very less time for this to get executed, approx. 3-5 sec.).
An Android app like the one you described will likely drain the device’s battery prematurely. This is the simple reason why Apple has restricted background execution to a clearly defined set of tasks:
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
Apps 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
This list is taken from Apple’s official description of background tasks: Background Execution.
Related
I have a VPN-Client app that asks the user to pause the connection for 5, 30, and 120 Minutes. The user probably leaves the application to do some work outside of my app in this period, therefore I need to Reconnect the app even if is in the background.
I tested these ways:
UIApplication.shared.beginBackgroundTask: It only leaves the app unsuspended for 30 seconds.
DispatchQueue.global(qos: .background).asyncAfter: It waits to app enter the foreground to toggle.
Thread.sleep in Background Thread: This waits to launch as DispatchQueue
Local Notification: Unfortunately it does not support silent mode as APNS.
My problem with possible ways:
Using APNS and Scheduled Push Notification` to send a silent message: This way probably works, but I prefer to handle it without a server.
Using Background Fetch from Capabilities in Background Modes: I searched a lot about this, and I think it was used for background app refresh and cycling tasks that should be run every day, hour, etc. Therefore, my case can't be used, or it's not efficient at all.
Using Background processing from Capabilities in Background Modes: I searched a lot about this too, I didn't quite catch that it can be used once, or this should be used in a cyclic way as Background Fetch. and my task to reconnect is not that heavy and long to use this strict feature that many times apple mentioned using alternative ways if possible.
Apple only allows a very limited set of app types to run in the background:
Music streaming apps, turn-by-turn navigation apps, VoIP apps, and maybe one or 2 more. (I haven't looked at this in detail for a couple of years so my info is a little stale.)
They do support various tasks like background downloading that the system performs on your app's behalf, but you want your app to re-launch after the designated period and start running again. (Even if the user just locks their phone while your app is paused, the app won't get any CPU time and may be terminated without warning.)
In short, I suspect you are out of luck.
It seems like a VPN app is another class of app that should get "always running in the background" status.
If you are a licensed Apple developer I suggest using one of your pre-paid support tickets to ask about OS support for what you are trying to do, but I have a feeling the answer is going to be "no dice."
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.
This question might be duplicate of many others but I am still asking because I really need to get any solution of it.
For iOS versions prior to 6, for devices other than those having an A7 chip.
I have an application which interacts with the Accelerometer. I am also running it in background by playing a sound file and turning the Audio services ON for background task.
Now If any third application plays music, it takes control of shared Audio Session of device which causes my background thread to call completion handler assuming that background task has been completed.
Now my application is interruptible by iOS and iOS can kill it if it remains in background for a long time after which I couldn't interact with accelerometer.
Is there any way/trick/hack to keep my application running all the time until unless I kill it by my own.
Again, this is a duplicate question but I really wanted to share my problem with you people to help me in this sense.
Apple is very clear on this:
Implementing Long-Running Background Tasks
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.
Apps 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
Collecting accelerometer data is not listed. Therefore, what you are trying to do is not possible. "Ways, tricks, hacks" tend to get discovered quickly and offending apps removed from the App Store.
I need my iPhone app to do some tasks in the background when it's suspended, but I don't need to do any tasks after it's turned off. Do I need to settle UIBackgroundMode?
Yes, to execute code continuously in the background state, you need to register for a given UIBackgroundMode.
See here or here for a good source on this.
However if you just wish to perform a single background task (task completion), you don't need a background mode.
In response to your comment below, I will try to be clear:
In iOS, even in iOS 7, it's not possible to run arbitrary code when your application is in a background state indefinitely.
In simple English, - you can't just run any code you like in the background for as long as you like.
There are rules.
These rules have been relaxed somewhat in iOS 7, but it's still not totally unrestricted.
Consider your situation: You have a timer that wants to call a method on a continuous basis.
Now consider the UIBackgroundModes available (which allow you to run in the background in various situations):
audio - Only for audio based apps.
location - Only if you app is location aware, does specific location tasks
voip - VOIP (Skype etc)
fetch (Background fetch - a new iOS 7 API where the system gives you application moments to grab new content when it sees fit.
remote-notification - new in iOS 7, when the device receives a remote push notification with a certain payload, it will resume and execute a certain block of code.
newsstand-content - Only for newsstand apps
external-accessory - Only for external accessories to communicate with the device
bluetooth-peripheral Only for external BT accessories to communicate with the device (fitbit)
As you can see if you don't fall into one of these categories you can't use these modes.
If you misuse the modes Apple won't approve your application.
Finally we have 'Background task completion'
This is a way to use a UIBackgroundTask to execute any code you want in the background! Including timers that call methods! - One problem though...
This is supposed to be for 'task completion' (Facebook uploads that aren't complete, saving or processing data that should be done before the app suspends even though the user pressed the home button).
Sounds good, but you can only run in the background using this method for a maximum of 10 minutes. If you go over this time limit iOS will immediately kill your application.
So as you can see, there is no way for your application to be approved on the store and constantly run in the background with a timer that calls your method.
Sorry about that.
If you want to learn more check this out.
Use the location service and set NO location manager "pausesLocationUpdatesAutomatically" property.
I was trying to run some services in the background so I struck the control in the background by using a while(1) loop in the background delegate for some time.
On the emulator it is working fine but on transfering it to my iPad, the app is crashing after going into the background.
Does the while(1) loop not work for on the device?
On emulator it is working fine but on transfering it to the Ipad device , the app is getting crashed after going in to the background.
If I interpret correctly this that you are writing, what I think is that your app gets killed on iOS devices simply because you are not allowed, except in a few spare cases, to run a thread in your app when the app is "in background" (i.e., after the user has "quit" it by clicking on the home button).
So, if I am right in my reading what is happening, either your app is in a specific class of
apps (see later), or the only thing you can do is "registering" a background thread to run for a limited amount of time after the app goes in the background.
Excerpt from Background Execution and Multitasking
Most apps are moved to the suspended state shortly after entering the background. Only apps that provide important services to the user are allowed to continue running for any amount of time.
As much as possible, you are encouraged to avoid executing in the background and let your app be suspended. If you find you need to perform background tasks, here are some guidelines for when that is appropriate:
You need to implement at least one of several specific user services.
You need to perform a single finite-length task.
You might be especially interested in the "Implementing Long-Running Background Tasks":
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 keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Newsstand apps that need to download and process new content
Apps that receive regular updates from external accessories