I am looking for something that is equivalent to Services in Android. As far as I have searched I haven't found anything useful. I found Background Fetch but according to my understanding it cannot be used long processes.
Here is what I want to use it for.
fetch a list of twitter user ids from our web server then auto-follow those usernames in background. As there are limits in Twitter API, so the process will be long possibly 3-4 hours. Is this possible on iOS?
There is no long-running background mode for continuous execution of apps in iOS.
This doesn't really sound like the right task for a mobile device. Running a 3-4 hour background job would be bad for battery life.
You can implement the function on a server somewhere and use push notification to send updates to the device.
An Android Service use case that is often cited is a background music service, which I have implemented as an exercise. It is not a given that a long running task actually will consume a lot of battery. Rather, it appears Apple is guaranteeing that such an event cannot happen through API design.
Related
I would like to know if there are limitations regarding how often I can execute something in the background. I found this library : background fetch and it says that on the iOS part I cannot execute it more often than 15 minutes.
Are there workarounds for this?
My purpose is to check in the background the available Bluetooth devices detected and to send them to a database.
I only have experience in android and I'm not sure how to convert it to iOS or if it is possible.
Yes, there are limitations imposed by iOS. It will decide when your app is given time to execute background tasks such as a fetch of web data. It can be more frequent than 15 minutes but on average it may be every 20 minutes at best. It might be two hours or more. We are not privy to the algorithm and cannot predict the result.
Known factors are power state, how well your app conforms to the rules and gets its work done in the time allotted, and some measure of how (and when) the user uses your app. Low battery? Fewer background tasks allowed. User never uses the app before 8AM? Few fetches called overnight. It's all beyond developer control.
A developer can use a timer to trigger a routine task but it's only relevant if the app stays active in the foreground.
Im quite new to iOS programming and now want to implement a periodic background synchronization to synchronize my server data with client data. What I want to achieve is comparable with Androids SyncAdapter where you can define a time interval (for example each 30 minutes) and the system will trigger the defined task automatically in the background.
Until now I could not find such mechanism for Swift 3.0 so I need to ask if somone has experience or some hints for me how I can achieve this.
What I want to do sounds quite simple:
When the app starts for the first time the app should setup a sync manager which automatically triggers a background task every 30 minutes. The background task is responsible to synchronize server and client data (using Alamofire).
How can I do that?
There is an iOS feature called BackgroundFetch, which you can set up for
regularly downloads and processes small amounts of content from the network
You can setup a minimumBackgroundFetchInterval.
In contrast to the mentioned Android feature, this interval is not guaranteed though.
The OS does some heuristic in a blackbox. It rewards you for using a "reasonable" (to the OS) CPU time/ power consumption and also for being used often by the user. On the other hand you get punished for draining the battery or (even worse) never being used/opened by the user.
See: Apple Sample and Apple Docs
Update: Since iOS13, BackgroundFetchis deprecated.
There is a similar, new API named BGTask, BGAppRefreshTask is the equivalent to deprecated BackgroundFetch.
See Apple Docs
Alternatively, depending on your needs, you can post a Silent (push) Notification whenever the users data changes on server side. A silent push wakes up your app without notifying the user, so you can fetch data and maybe inform the user by scheduling a local notification.
See: Apple Documentation
You can't. Apple doesn't allow 3rd party apps to have regular background time like that. You'll need to come up with another approach like implementing a silent push notification from your server when new content is available.
As #ekscrypto points out in their comment, you can use Background fetch to load small amounts of data when the system decides to fetch it. However, you don't have any control over when that fetching takes place. Search on "Fetching Small Amounts of Content Opportunistically" in the Xcode help system for more information.
In my application I need to log user status every 15 minutes. Is it possible if the app is in background (not killed)??
Currently I enables the Background location update. But how to call in each and every 15 minutes
While other answers are correct about background fetch, there is also another background option called VoIP, which apps like Skype use. In this case OS will wake up your application more frequently (even every 10 minutes if I remember correctly) and you can keep pinging your server in background. The obvious down side is that your app must have Voice over IP functionality, otherwise it would get rejected on the App Store.
All you need to do is add call setKeepAliveTimeout:handler: method and have voip enabled in background capabilities.
Just adding this for the sake of completion.
You may want to look at the Background Fetch capabilities added in iOS7 and beyond:
http://www.appcoda.com/ios7-background-fetch-programming/
https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html (Search for background fetch)
You won't be able to control the interval to exactly 15 minutes but you will find that this mechanism is the closest Apple will allow.
It is not possible to perform network calls at clearly specified intervals when your app is in background mode. You can tell your app to use background fetches
This article gives a great overview on the capabilities that you can do with this API. Basically it allows you to tell iOS that your app wants to perform networking calls in the background, however you can't exactly control when and how often iOS the network calls are going to be performed. iOS will schedule your network calls for you, and depending on how your app is used it will adopt the frequency with which it performs the requests. Documentation can be found here.
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 Googled around and I can't find many discussions on this. I want to develop an iOS program that would use access a REST service, and I want to get notified of updates so I am thinking of long polling. Does RestKit deal with this?
Another questions is what if I want to run in the background? It seems like the proper way to do is to set up an Push Notification Service and notify the user to open the app to receive the latest message?
Doing a job in background is only possible with special APIs like Music and Location, so you won't even be able to do queries if the user is not using your app.
Instead, you should do all the heavy work on a web service, and setup an APNS server to notify the user when something happens. That way, it won't drain all the battery of your users and use technology in place exactly for that purpose.
There's also a lot of service to send out push notifications, if you don't want all the heavy setup. Take a look at http://parse.com or http://urbanairship.com/.