I am working on a Win8-UI-App (previously called Metro...) and trying to implement Periodic (Documentation for different methods) Tile Updates (Live Tiles) for the first time.
I found a couple of very good resources on the internet and was able to do it. Unfortunately the question of where I should register for the notifications remained unsolved:
Do I have to register for Notifications every time the app starts (e.g. in the App.xaml.cs OnLaunched() Method)? - Or is there an other, more professional way to do so? (I could imagine to save if I already registered for the service or is there a variable I can access to see whether notifications are registered?)
thank you!
PS: For everyone who is also new to this see this StackOverflow post, this example, the tile template types and the Dev Center for quick starting :)
Periodic updates will continue until they are explicitly stopped or your app is uninstalled. Technically, you only have to do that once. But, the Guidelines and checklist for periodic updates states
Call the StartPeriodicUpdate or StartPeriodicUpdateBatch method each
time your app is launched or brought into focus. This ensures that the
tile content will be updated each time the user launches or switches
to the app.
According to that, App launch and App resume are good candidates for a call to StartPeriodicUpdate.
Related
I have an application where I need to create local notifications via polling without doing push - primarily due to client infrastructure limitations and their security model.
I've read: http://www.objc.io/issue-5/multitasking.html, I've seen David Chan's WWDC presentation - where single push messages kick off download tasks - but what I truly need is background fetch - on a regular basis - like every ten minutes - in iOS 7.
I've seen the VOIP hacks. No. What non-hack way is there to do this without user interaction or push messages? Any examples you can point me to?
Here's what I know:
Background data tasks will work in the debugger but if you can get a console on an IPA, you'll quickly find out they really are prohibited (thereby invalidated many examples).
Background URL tasks require custom delegates - but fetch completion handlers are iffy. This too I found with an IPA and console.
I would love to avoid using the AFNetworking lib - for something quite simple.
Background fetch is not a reliable solution - you are at the mercy of the OS, and it is not very merciful. Abusing iOS background modes is not a reliable solution - Apple is known to reject applications that enable background modes, such as location, VOIP and music playback, without a legitimate reason. Background URL tasks are not something you can rely upon to wake your app; they will wake it, but the app will not be awake enough in the background to enqueue a background URL task.
Your best and most intended method is still background fetch, but be prepared to be disappointed. Your app will not be woken app in the interval you need. Also, the user can kill the app in the app switcher screen, causing your app to never wake up until opened.
No real reliable method other than push. You need to insist with your client for the sake of user experience.
Unfortunately there is no "reliable" way to do that on iOS. With the background fetch API you are not guaranteed to have process run when you would like it run. As you've said, you've already looked at the API so i'm probably telling you something that you already know. A local notification wouldn't solve your issue either as this isn't a way that you can wake your application up and kick off network events. This is behavior that Apple doesn't want as this would negate the whole purpose of their background task coalescing.
You really need to have a push mechanism in place for something like this, so if this is something that is needed, then you may have to stress that to the client.
When we deactivate a WP app, it can be tombstoned and terminated later by the OS. I need to save some unsaved app data to a persistent storage when the process is terminated, but not before this. Obviously, the Deactivated event cannot be used for this purpose as it is raised immediately when an app is moved to the background; the Close event is also not the event we need as it si not raised when the app process is terminated by the OS. Is there a special Windows Phone app event for that, something like Application_Terminated?
The problem is that the operating system only tombstones your app when it is under severe resource pressure. At the time it is not practical to wake up the app and run app code because it might risk whatever is currently in the foreground. This limitation exists on all modern mobile operating systems (Android, IOS included). This is just the cost of operating in a battery/resource friendly environment.
Having said that, it sounds like your backing store does not disambiguate between data the user "saved" and data that is just being cached until the user can finish the transaction. It would be useful to build the idea in. Think of it the way some of the smarter web sites on the internet now work. You can navigate away while you were in the middle of entering data and when you come back the site presents you with the partially filled form. The site understands that you weren't "done" but it respects the fact that you had provided some of the information you'd need to get "done".
What I'm saying here is that the problem is easily fixed by understanding and accommodating the way your users are likely to use the app. Thinking of your app like a web site (at least in this context) helps out things into perspective. Sorry about the longish answer. I hope it helps :)
There is no such event. You should save your state on Deactivated so that if the application is removed from memory (tombstoned) you can set yourself up again upon reactivation. If your problem is figuring out whether or not you need to restore state on Activated, check out the ActivatedEventArgs.IsApplicationInstancePreserved flag (http://msdn.microsoft.com/en-us/library/windowsphone/develop/microsoft.phone.shell.activatedeventargs.isapplicationinstancepreserved(v=vs.105).aspx). This flag tells you whether your app was tombstoned. If it wasn't, you can throw away the old state or overwrite it the next time you are deactivated.
So I've read that in iOS, all timers will pause when your app is running in the background. I've also read that you can run tasks in the bg using beginBackgroundTaskWithExpirationHandler (like so).
What I am trying to achieve is to call a method once every 3 minutes, and another method a fixed-amount of time before the first one. I have managed to do this within one NSTimer which repeats in a way that lets me do this. It works fine but is obviously disabled (or paused) when the app is in the background - I can only assume because of the reason described above.
Does anyone know if there's a way to run a timer or at least call something after a specific amount of time so I can do this?
Basically if you want to continue running active in the background you have to meet one of the following requirements. From the Apple docs:
Implementing Long-Running Background Tasks
For tasks that require more execution time to implement, you must
request specific permissions to run them in the background without
their being suspended. In iOS, only specific app types are allowed to
run in the background:
Apps that play audible content to the user while in the background, such as a music player app
Apps that keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Newsstand apps that need to download and process new content
Apps that receive regular updates from external accessories
Apps that implement these services must declare the services they
support and use system frameworks to implement the relevant aspects of
those services. Declaring the services lets the system know which
services you use, but in some cases it is the system frameworks that
actually prevent your application from being suspended.
http://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html#//apple_ref/doc/uid/TP40007072-CH4-SW24
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.
I started off on the Win8 metro app (javascript) development recently. For notifications, it is clear how the WNS notifications will be useful for creating live tiles.
However the use case for local notifications is not clear to me. I have these two questions:
is it correct to assume local notifications make sense only for apps that would run in the background e.g. when other apps are running or when the system is locked?
if the above is not true, then kindly suggest some examples of when local notifications will be useful.
regards
CGere
Local notifications are useful to update your tile on the start screen that persist after your app was closed/suspended. For example you might want to update the tile when your app closes with some context, perhaps an image from the last level of the game they were on or such.
When your app goes to the background it has a short period of time to suspend after which your app will no longer be running and thus unable o update the tile. You can however create a background task to run on an event/timer to do some work (such as update your tile).