I'm new to Swift and iOS app development, and my boss wants me to fix the iOS app. The user has an option to start listening for events from someplace (using alamofire's AF.streamRequest), and then when it receives a response from that place he wants the app to create a new api request and send that out (based on the response).
The way the code is implemented, the app stops listening as soon as it goes into the background or is terminated. Sometimes when the user comes back into the app - after it was in the background but not terminated - the app will receive the missing events, other times it errors out and the stream request stops entirely.
Is there a way to make a persistent connection work on an ios app even when the app is in the background or terminated?
Any help would be appreciated.
Thank you.
If the app is terminated by user there is no way to wake up your app again.
Running your app in background is only possible for some specific tasks like play music, ...
Take a look at the documentation: Handle Background Events
Related
I want my iOS Swift app to run in the background. The things I want to run in the background are:
Timer - that pings server periodically and retrieves data from it and then its displayed on the tableView.
Audio - If a certain condition is encountered in the retrieved data, I play a local audio clip from the app via the avf framework.
The app is working as expected. I have done the following to allow backgrounding:
It does work in the background. However, is there any additional thing that I need to do? such that the app doesn't get rejected from the Apple App store.
“Timer That pings the server periodically” - that will make Apple hate you. And if Apple allowed it on the App Store, users whose battery you are emptying will hate you.
Read up on push notifications. No pinging, no energy use at all. Doesn’t even use WiFi or mobile data - your phone service provider sends you the push at a level below mobile data.
We are building an iOS iPhone app that needs to check-in with a server on a 12 hour basis. This is needed to let the server know that the app is still using it's service on the server. To our understanding this is possible when the app is in background state (not showing on the foreground) via backgound fetch or remote notifications.
But this is not possbile when the app is not running or terminated, when the app is in these states then there is no way to initiate communication with a server. Is this statement corret? Is it possible initiate the communication after a device bootup, is it then possible to send a small keep alive message to te sever?
The background fetch and responding to remote notifcations is not possible in the not running and termenating states(?), so we cannot use these mecahnisms for this purpose. If that is the case are there any other solutions that we can try? Or is it just not possible?
We looked at many sources on the internet but some say that it is possible and others say it is not.
You might want to take a look at the Silent Push Notifications. Here is the thing, if the app is in background mode or suspended state, you will be fine. If the app was killed by the user, you have a problem.
You can always send a silent push notification, and wait for a service call made from the device to your service. If there is a response, it means the app was in background or suspended, and then you can go ahead and do whatever you need to do. If no request is made, it means that app was killed. Then you might want a sent a non silent push letting the user of that device know that he needs to launch the app or something like that. I don't know how you are going to work around it, but that could be a possibility.
I would tell you to take a look at NSURLSession and Background NSURLSessionConfiguration as well, but you will run into the same issue. If the user manually terminates the app, you need to find a work around to set up that connection to the server, and that will imply the user to somehow launch your application.
I am working on Poker app based on server-client based app. When Poker App goes to the background after some time TCP/IP connection lost because app unable to send/recieve any packet to/from the server. Sever ends socket connection. how can i able to establish connection for long time and update my game UI
The topic you asked for, is called "Background Execution".
First:
You can't update the UI while the app enters the background. But you will be able to finish your API-Requests to the server and save the data on phone while using beginBackgroundTaskWithExpirationHandler. You can use this method to write a block which communicates to your server and handles all the data your app will receive. If the App enters the foreground again, you can use this data received in background to update your UI then.
It is important, that those background tasks have to finish in a short time, so it will be not a good idea here to have an infinite loop. Otherwise, iOS will terminate your process. How much time you really get after your app gets backgrounded is determined by iOS.
Second:
If you want to keep tcp/ip-connections always on even if the app remains in the background, Apple provides a very powerful background mode which enables you to run code for any time in the background. It's called VoIP-Services. Unfortunately your app should provide some VoIP-Stuff to not being rejected by Apple. Here is a good article about those services.
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
How does Navita https://itunes.apple.com/us/app/navita-t.e.m.-personal/id590228620?mt=8
manage to display a call log?
If I swipe the app out of the task manager then it misses the calls, this indicates that it must presumably be using CTCallCenter's callEventHandler and is creating its own call log by saving the time/duration in response to the callEventHandler callbacks.
However if that is the case then how does it manage to do this in the background? I was under the impression that callEventHandler can only be used by apps in the foreground and not in the background?
The app is using location services, however even after disabling this it was still able to get information about the calls (provided the app isn't suspended). I though it might be using background location updates to keep itself primed to receive callEventHandler callbacks but apparently not.
The Navita app is additionally able to display call time and call duration.
The bounty will be awarded to an answer which contains sufficient, accurate and detailed information that enables me to emulate the behavior of the Navita app, specifically I must be able to write an app that can obtain the time and duration of a phone call that occurred while the app was not in the foreground, while the device's location services was turned off, and after the app had been in the background longer than the ~3 minutes granted by using beginBackgroundTaskWithExpirationHandler:
Here is what I observe with the Navita app that I want to be able to reproduce:
1) Run app
2) Task away from app
3) Go to device settings, privacy, and turn off Location Services.
4) Go to device settings, privacy, background app refresh and turn off for the app
5) Wait > 10 minutes to make sure the app is not still in the background as a consequence of using beginBackgroundTaskWithExpirationHandler:
6) Call the device from another phone, answer the phone call, then hang up.
7) Launch the app again and display the call time and duration
(This is iOS7 and unjailbroken)
Here is what I've found from Navita TEM disassembly and it's resources.
Application uses two background modes - location and audio. You can see it in the Info.plist file. When you enable phone calls logging application will also enable "alerts" and "Real-time" switches. When "alerts" enabled application infinitely loops in background "bg-sound.mp3" file which has no sound, it's just silence. Because of that it doesn't use hacks like this one How to get a call event using CTCallCenter:setCallEventHandler: that occurred while the app was suspended? . It's similar trick to location used in order to keep the app running in background and receive phone call events. Somehow this was not rejected from the AppStore.
If you are observing the call center while the app is in the background you get a set of updates when the app is brought back to the foreground. This set of data may not be as accurate as if the app had been mostly in the foreground but it does include quite a bit of info.