For a project I need many clients to subscribe to different hardware devices. In this setup the clients are iOS - Devices. The hardware is something like a raspberry pi but i don't think this matters. This hardware devices send a signal if it measures some kind of information. This is a rare event and possibly could never happen.
Purpose of the app is to warn the user when some kind of event appears in a location he is interested to.
I planed to implement this using the MQTT protocol.
That is where my problem is. To work with MQTT the app needs to send PINGREQ every few minutes even when the app is in background. Also the app needs to receive its subscriptions and handle them immediately.
This is what I planned to do:
Set the "UIBackgroundModes" key in Info.plist to "voip".
Mark the socket as voip socket to wake the app when it receives something
Set the keepAliveTimer:callback: and send the PINGREQ
.. as described here
My questions are: Will Apple allow this? My app is not an VoIP app. If no, are there any alternatives to this approach?
If Apple policies doesn't allow your to put your MQTT client App running in the background, then the solution should be to implement an additional push service.
A push service subscribes to your MQTT broker and sends push notifications to your mobile devices, so that either they have the MQTT client App running or not they will get the events.
Yes!
There is a chance that apple can reject your application when you are using VOIP(even though your app is not a VOIP Kind of application) to keep application alive!
I'm using Location services which is a proper solution to keep application alive in background mode.
Ask permissions to use location services even when the app in background mode & after getting the allow call back,set your location manager's desired accuracy to worst,distance filter to 99999(means your app will be notified if the user travels more than 99999 Meters from last location update call back)
By altering the desired Accuracy and distance filters you can save the user's battery consumption,otherwise your app will consumes lot of energy
That was one proper way which makes your application to run in background for more than 2 days continuously (Already using in our projects).
HTH! Have fun in coding :)
Related
I have an idea for an app that utilises Live Activities, inspired by the Flightly app (it starts a Live Activity for a plane ride): Basically I wanna use open data from an HTTP endpoint that is reachable via the onboard WiFi on a bus. E.g. you board the bus, connect to the onboard WiFi, open the app, it fetches details about the stops and then you start a Live Activity guiding you to a selected stop. So far so good. But sometimes the bus faces delays, etc. In that case, I need to update the Live Activity. That is easy when my app is running. It is not so easy, when my app is not running (or running in the background).
What is my best approach to regularly fetching data from the endpoint and updating my Live Activity? The problem is, that the endpoint is only reachable on the buses WiFi. So it looks like I cannot use APNS to push updates to the Live Activity (since my service running outside the bus cannot access the endpoint that provides the details and thus cannot push any meaningful updates). Background Tasks (e.g. background app refresh) run infrequently.
What options are left? I thought about receiving location updates in the background and acting on them to update my app state (and possible the Live Activity, if needed), although I haven't investigated that path in detail, yet.
Has anybody faced a similar issue and found a solution or can provide some guidance on how to approach this problem?
I think the easiest option is core location. So keep your application running by monitoring the position and then you can update the Live Activity by fetching the information from your access point. It should be fine for app review since you could use the the location to show a position on a map and only while the person is on the bus.
If your application isn't running you have to send the ActivityAttributes via APNS. Since the data cannot be accessed from a remote server that would communicate with APNS there is no direct way to use ActivityKit push notifications. An indirect approach (which I would not recommend) would be to send silent push notifications triggers every 5min or so and fetch the newest information when the application is woken up. But this won't work when the app is force-quit and using silent pushes to trigger polling will give you a bad score by the system and eventually the frequency will be throttled from APNS.
Is it possible to simultaneously broadcast my iOS app as an iBeacon and at the same time publish a service?
My app currently advertises a service, which works perfectly fine. My client app (central) is able to find the peripheral, connect, obtain the service and read data from the characteristic. However, if I update my server app (peripheral) to start broadcasting as an iBeacon emitter in addition to the service, I am no longer able to find services that I setup to advertise on the client app (central).
The idea of this is that I want to be able to read information from the server (peripheral) app when in close proximity from the client (central).
Is this technically feasible?
I was thinking about turning off iBeacon transmission when a device comes into close proximity and then starting the service broadcast, but there is no API in Core Bluetooth that calls back to the emitter when a client device enters the region being advertised.
Is this doable? Is there a workaround that would achieve something along these lines? I would like to avoid any networking, as this should be an offline solution.
Taz, For sure you can be an iBeacon and you can look for iBeacons. What I did and what I see other doing is combining iBeacons with other services, such as the CloudKit [which yes, means networking too] to add functionality to their basic functionality.
That said I can imagine an app in which your iBeacons switch to a different protocol when they see each other, the challenge; how-to negotiate a channel/UUIDs for a BLE peripheral/central pair.
I am still in the process of building, but have implemented something similar over the past months... in short you hardcode an initial channel to start your BLE conversation, your first and only exchange on said channel being to agree a new BLE one to use.
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 have a chat application developed by JS. I want to send PING to server once in a while. Its not a problem if app runs on fore ground. The problem is when user minimizes it or open another app. My app looses its focus and gets into suspended state.
I have following two use-cases.
To keep the chat session open I need to send PING to server (Its an IRC server) every X minutes even the app runs in background.
We also need to check for new messages (by ajax on a local http server) and add a local notification to the notification queue so when user clicks on it app can resume
I have found apple does not allow running apps in the background. if they allow they require special permission. I found some apps does it by requesting finite length execution time.
What is the best way to get highest possible background execution time? As a chat app can I request permission for voip, location or any other way ?
Note: the app will be running in an environment where there is no Internet. Hence push notification will not work here.
Update: After doing a lot searching I found background fetch. It seem background fetch will suite it. But still the problem remains, its not called in a timely manner.
This sounds like an interesting problem. From reading the various comments, it sounds like you want this to work when you're on a local network - so you have wifi, but the wifi router/base station isn't connected to the actual internet?
Because background refresh isn't going to be predictable - you'll never know when it is going to update - you might want to get creative.
You could look into exploiting iOS VOIP support, only without the Voice! Apple has some tips on VOIP here. VOIP basically uses something called SIP (Session Initiation Protocol), which is signalling layer of the call, and a lot like HTTP. It's this SIP layer that you want to take advantage of.
This isn't going to be terribly easy, but it should be achievable. Setup your app to use VOIP, and then look into something like PJSip as your SIP library. Then, on your local network have a SIP Server (I'm sure there are plenty open source implementations) that you can register your iPhone against (so your server knows where your phone is, pretending to be a VOIP phone). This should work, because it doesn't need to go through Apple as far as I am aware... And will run happily on your local network.
Then, the server can send a message via SIP to the handset, as if it were instigating a VOIP session. You app is awoken, gets the messages - ideally from the SIP message if possible - and then just doesn't start the session. SIP was designed just for creating sessions, not just VOIP. When I worked in Telecoms R&D (a long time ago) we were using it to swap between Text/Voice/Video, all using local servers.
You'll have to jump a lot of hoops to make this work, but it would be pretty awesome. I have never tried this actual use case - especially with iOS, but I'm fairly sure it will work. It is a bit of a fudge, but should get you where you need to go.
Good luck!
You can use something like PubNub to build this chat app with iOS using native Objective-C code, or with the Phonegap (Cordova) libs.
The beauty with using a real-time messaging network like PubNub is that when the app goes to the background, you can easily have the chat messages come in on APNS.
When the app is in the foreground, it can just receive them as the native (PubNub) message. And if it needs to "catch-up" with the messages it missed while in the background (but received via APNS), its trivial to implement.
Also, PubNub is platform agnostic -- so you can easily also use it on Web, Android, BB, Windows Phone, etc.
http://www.pubnub.com/blog/build-real-time-chat-10-lines-code/
http://www.pubnub.com/blog/html5-websockets-beautiful-real-time-chat-on-mobile-using-pubnubs-channel-presence/
https://github.com/pubnub/objective-c/tree/master/iOS
https://github.com/pubnub/javascript/tree/master/phonegap
geremy
I have a requirement to develop an app that is capable of receiving pushed information from a server - which as its not possible to intercept SMSs or apple push notifications would probably have to be implemented as a poll and see what's there or similar type of thing.
However of course such a thing isn't possible if the app isn't executing in the background.
The app couldn't be considered to be musical or voip related, however its possible that it could be considered to be gps related as the pushed information would be displayed to the user based on certain triggers, and one of those triggers could be location.
Would this app with a UIBackgroundMode of gps submitted to the app store stand a good chance of being accepted?
i have been trying to do the same thing and here is what i found
iPhone - Backgrounding to poll for events
(top answer: update 2)
shows a method that should be ok, meaning your app wont be rejected for using it. the guy who posted it said it should be ok and i have asked other members who said the same (i have not verified this myself).
here is my implementation of that post
local notifications?
You don't have to use a hack for your requirements.
iOS provides a facility whereas your application is suspended but your socket is still monitored. If there's any incoming traffic on the socket, the app is woken up and handed back the control of the socket.
Advanced App Tricks
Look under the heading, "Tips for Developing a VoIP App"