I have an app that runs for a while, but needs to be reset every day, because it's lifecycle is a bit different than most other apps. It seems that the easiest way to do this is to kill the app and re-launch it.
I found a solution that kills the app when the home button is tapped:
In your application's Info.plist, add a boolean key
UIApplicationExitsOnSuspend with the value YES
This is not something that I want to do. I need to give the user an option to kill/reset the app before it is used. I can certainly ask the user to double tap the home key and kill the app with a long press>x. Yet this is too complex for some users.
Another simple solution would be to have a button do something crashworthy, like divide by 0, although I'm not sure if the app store would penalize my app for "crashing" every single day for all users.
Has anyone found a way to add an "exit" button to an iPhone app? In android, I could do system.exit(0), which worked. What's the iPhone alternative?
iOS Human Interface Guide says -
Don’t Quit Programmatically
Never quit an iOS application programmatically because people tend to
interpret this as a crash. However, if external circumstances prevent
your application from functioning as intended, you need to tell your
users about the situation and explain what they can do about it.
Depending on how severe the application malfunction is, you have two
choices. ...
exit(0); can terminate the application (0 is a normal code), but Apple don't like this approach, and the application would be rejected in review.
Related
I'm currently working on a kiosk type application that won't be distributed on the App Store. The device will sometimes need to switch applications to handle some other tasks, but in the case where a user doesn't manually switch back, I need my app to come to the foreground after a set amount of time has passed.
We don't have control over the other apps, so getting them to switch to ours after a timeout isn't possible.
I know this can't be done through official means, but I'm asking if anyone knows of a private API I could call from within a scheduled notification that will foreground my application.
I have a feeling that this cannot be done without a jailbreak due to the sandboxing nature of the apps, as in, there's no way to send a message to whatever service launches apps on the device. Although it should be possible, as the demo devices in the Apple stores are able to revert back to a demo "screensaver" app if left alone for a while. What are they doing to achieve this?
If there is a jailbreak hack for this to work or a config or something an MDM service could handle, I'd be happy to try that out.
Again, this is for a private application that will not be distributed on the App Store. The app will be placed on devices located throughout our building and running on our internal network.
Via Jailbreak you could look at something like AutoLaunch:
If you use a particular app that seems to crash here and there, then a new free jailbreak tweak called AutoLaunch could be your next best friend. It can automatically re-launch any app that crashes on your device so you don’t have to re-launch it yourself.
http://www.idownloadblog.com/2017/01/08/autolaunch/
Not sure how much control you'd have over wanting to launch regardless of whether it's crashed or not. You might be able to ask the author to provide the source-code or work with him to get your desired result.
UPDATE:
It's open source:
https://github.com/chenzhijie/autolaunch
Upon further inspection of the source it looks like it uses the following to launch the application after a crash:
int createSubProcessResult = fork();
if(createSubProcessResult == 0) {
execl("/usr/bin/open","open",[currentAppBundleId UTF8String],NULL);
}
I guess you could roll your own version of Autolaunch and have it wait/subscribe for a remove command that'll launch/switch different apps.
i have a big problem. I am working on an app about accessibility. The app should work through the iPhone microphone to take over sounds from the environment (indoor) and compare them in real time with sounds in the app database (recorded from users previously). If sounds match, the user will be warned by the app through a notification. So... firstly, the app should listen sounds working in background, but after some minutes, iOS closes the app in background automatically. IS THERE SOME SOLUTIONS FOR THIS PROBLEM? TO ALLOW THE APP BE OPENED AND WORKING?
Secondly, do you know in which way is possible compare sounds recorded with sounds listened by microphone in real time?
Really really thank you. 🙏🏻
Regarding the problem that your app is automatically closed, it seems that something was not configured properly in your project.
When the UIBackgroundModes key contains the audio value, the system’s
media frameworks automatically prevent the corresponding app from
being suspended when it moves to the background.
Make sure that you have enabled the "Audio, AirPlay and Picture in Picture" background mode in your project.
Fore the first question:
Because your app will be recording the audio while in background, you can:
set UIBackgroundModes key in your app’s Info.plist file to audio.
It should keep your app alive when you press Home button. See the Declaring Your App’s Supported Background Tasks section
At some point, iOS can kill your app due to some conditions, but
eventually it would restart your app later.
And be careful with this, you might have to deal with Apple Review team to prove that your app is not doing something harm to user privacy. Otherwise, they wouldn't let it go live.
For the second question:
I think you can use some AI/Machine Learning service out there to do so. It's much more accurate and faster than building it your own.
Is there any possibility to know which apps are in the background (Those apps that appear when you double tap home button)?
For 3rd party apps, no. Not in a reliable, App Store safe, future proof way. Think of your app as siloed, unaware of what else is running, and you'll be pretty much in the mindset Apple want (and try to technically enforce).
For other apps developed by you, you can use shared containers to write load/unload data each time one of your apps opens/closes, and work out what's currently running.
This is not possible on iOS with public api. There might be private api calls that do this, even though I don't think you will have access to them while running in the sandbox. This however might be possible on jailbroken devices, but you will not be able to submit to the app store with such api usage, unless you know how to hide that from apple.
Also please note that apps shown in the app switcher are not necessarily running. The app switcher shows every app that has been running in the past which the user didn't force-quit. If the user does not force quit an app, every app that has ever been launched is shown in the app switcher. If iOS decides to terminate an app because of memory needs, the app is still shown in the app switcher. This is one of the reasons why everyone should implement state restoration, as the user does not know whether an app is currently running or not!
My app is an emergency app. It will be used by people in emergency and disasters.
It's possible that they got stuck in situations where they just don't have the time to enter or draw their password on the lock screen, launch the app and push a button. Is it possible that my app can ask the OS to launch the app if user throw their iPhone up in the air or shake it vigorously or something else.
What I wish to achieve by this ?
I want that OS launches my app in background if the user say shake his/her iPhone vigorously. Once launched my app will make a network request and keep running in background for short time.
PS:I think it's possible with the accelerometer.
Accelerometer will not work because Apple doesn't allow background processes opening apps. In your case, user must be opening the app by himself/herself manually. (PS. As far as I know, it's possible in Android)
iOS background tasking problems aside:
Apple don't allow apps that encourage the user to do things that might damage their iOS device. So your 'throw in the air' idea is out.
As for shaking the device -- this just isn't practical. What if the device gets shaken by accident? You've then got false alarms to deal with.
The crux of the issue is that something that triggers an emergency response should be a deliberate action which is hard to do trigger by accident.
This cannot work - and here's why.
Your app would need to run in background to handle motion events. Apps running in background can get killed at any time, i.e. if memory gets low. There might be some restrictions about running and and resource usage as well.
An app in the background cannot bring itself to the front.
Launching from a locked screen would bring great security risks.
Throwing into the air seems like a gesture that can easily be triggered by accident.
I must admit that I'm pretty happy that those apps are not allowed on the AppStore - as it would open many doors that I'd like to see kept close.
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.