I want to send data to my web server while the app is closed. Is that possible? I've read I can send the position, but I waant to send some id of the phone too.
If it's not possible to have the app running, could I at least communicate with it from my server and then do stuff in the background?
Thanks
When the app goes into the background the applicationDidEnterBackground method on your App Delegate will get called.
In that method you can use the beginBackgroundTaskWithExpirationHandler on UIApplication object to start background processing.
Just realise that you don't get forever to perform tasks in the background. You can find out how long you have left by reading the backgroundTimeRemaining property in UIApplication if you need to know if you're running out of time.
If your processing is short you should be fine, but remember if your processing requires network access then you can't be sure how long that will take.
Related
I am trying to make a chat app using XMPP protocol. The app is working fine except it doesn't show message notification when the app is in background. In Android I have used a Service for this purpose, however in Windows Phone I couldn't find anything similar to this.
I am trying Background Tasks for this, but as far as I have understood, they're made to run on prespecified trigger and I cannot add any custom trigger to it. In Android I have put my socket connection and parsing message calls in the service itself so that they can run on background too and the socket doesn't get closed even when the app is stopped.
So my question is, is there any similar way to do it in Windows Phone 8.1 (WinRT, not silverlight) or if Background Task is the only option, can you suggest a way to implement the notification functionality. I don't need the exact code, I just need a push to the right direction.
First: You cannot run a network connection in background.
Suggested way is using PushNotifications:
Either directly with a Toast Notification
Or with a PushTrigger to handle a Raw Notification, work out what to do
with it (who was it from, prepare data, etc.) and then create a ShellToast from it. Adds flexibility and improves user experience, but is quite complex.
Known downside: You have to use a server.
Only workarounds: Background-Tasks that checks for new messages about every 30 Minutes.
I have a question about using remote push notifications in background. I know that I have just 30 seconds to run my code and must invoke completionHandler after that.
But what if while my application is active in background I received one more push notification? What completion handler should I invoke in that case?
Currently I try to use the last one but the system crash my app and I get BKProcessAssertion.
I can try to update the logic and call each of them (or the first? or the first immediately when get the second?..) but I am not sure that it would be the best solution.
Thank you
Looks like I must to call all of them. I have tried to call the completion handler immediately after receiving the next one and crashes are disappeared. I asked Apple engineers about that and they agreed that solution
I have created a web-service app and i want to populate my view controllers according to the response i fetch(via GET) in main thread. But i want to create a scheduled timer which will go and control my server, if there becomes any difference(let's say if the count of an array has changed) i will create a local notification. As far as i read from here and some google results, i cant run my app in background more then ten minutes expect from some special situations(Audio, Vo-IP, GPS).. But i need to control the server at least one per minute.. Can anyone offer some idea-or link please?
EDIT
I will not sell the app in store, just for a local area network. Let's say, from the server i will send some text messages to the users and if a new message comes, the count of messages array will increment, in this situation i will create a notification. I need to keep this 'controlling' routing alive forever, whether in foreground or background. Does GCD give such a solution do anyone have any idea?
Just simply play a mute audio file in loop in the background, OR, ping the user's location in the background. Yes, that will drain the battery a bit, but it's a simple hack for in-home applications. Just remember to enable the background types in your Info.plist!
Note: "[...] I fetch (via GET) in main thread." This is not a good approach. You should never fetch any network resources on the main thread. Why? Because your GUI, which is maintained by the main thread, will become unresponsive whenever a fetch isn't instantaneous. Any lag spike on the network results in a less than desirable user experience.
Answer: Aside from the listed special situations, you can't run background apps. The way I see it:
Don't put the app in the background. (crappy solution)
Try putting another "entity" between the app and the "server". I don't know why you "need to control the server at least one per minute" but perhaps you can delegate this "control" to another process outside the device?
.
iOS app -> some form of proxy server -> server which requires
"babysitting" every minute.
What is the right way to check for data in remote database through http requests in objective c iOS. I am thinking of an nstimer that is called every 5 minutes. The nstimer will trigger a function with a thread in it. Is this the right way? Is this going to work when the app enters the background?
Any help appreciated.
The thread (as like all execution in your program) will pause when entering the background - and if it was waiting on a network response, that response will fail after the app returns to the foreground.
Moreover, you need to explicitly tell iOS when you are beginning a task that you would like to continue in the background (with beginBackgroundTaskWithExpirationHandler: on your UIApplication singleton) and when you have finished that task (with endBackgroundTask:). However, that is only up to a maximum of ten minutes, so I daresay you won't be able to, say, continue your NSTimers in the background. But yes, the method you have described is fine for when the application is in the foreground.
When my application loads, using the didFinishLaunchingWithOptionsi parse data from the internet to nsarrays. My question is, when the user exists the application by using the 'home' button, and then loads the application again how can the data be re-loaded? (because if the data does not reload - if there are any updates on websites, the new updates will not be seen).
Add an applicationWillEnterForeground method to your app delegate. Load the data there, or start a thread to load it if you like.
You should probably also periodically check for new data even while the app remains open, because the user could go idle for a long time.
As an aside, you shouldn't do anything which might block in applicationDidFinishLaunchingWithOptions. If you are using synchronous NSURLConnection APIs there is a danger the OS might kill your app for taking too long to launch. Best to either use the asynchronous/NSURLConnectionDelegate APIs or do the networking on a background thread and call back to the main thread when you need to update UI (UIKit does NOT like being called from background threads, as it is not thread safe. It might appear to work sometimes, but it will come back to bite you sooner or later).