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.
Related
I just want to find out music from my service is currently playing or not? Usually for our Android or iOS client we used to send a heart beat (ping) to service to notify client is alive, how can implement the same in SONOS. I've tried with getLastUpdate by setting pollinterval but it seems it is getting called only when my controller is in foreground.
Thanks in Advance.
We have several reporting methods that should help you accomplish this kind of reporting. reportPlaySeconds (http://musicpartners.sonos.com/node/388) is probably your best bet, as it will tell you how long a listener was listening to a track (and thus that playback is occurring) and allow you to set the interval at which this is reported back to you. In the future, reportPlayStatus (http://musicpartners.sonos.com/node/389) should also be able to help you track playback (although currently this is only reporting on skip events).
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).
I'm a new ObjC dev and after searching the Web and Apple's developer docs, I can't find a good succinct explanation of the various iOS device modes, and what goes on in these modes. I see a lot of little discussions, but nothing overarching about the big picture.
For example, I see that some Alarm applications for iPhone/iPad claim to be able to execute alarms (presumably not just system alerts) in the morning. I'm struggling to understand how that happens, even if the user lets the app just keep running overnight, assuming the device goes into sleep mode after no use.
So I don't know what happens when the device goes into sleep or standby mode. Is it just the screen dimming? Does the application in the foreground continue to execute code, go into some interim state like background mode in a saved state, or does it completely (even if temporarily) shut down?
I'd just like to be pointed to a website, a book or the portion of the Apple documentation that explains the various device states, what's going on under iOS 3 & 4 with the application in each state, and how to manage that if you'd like to build an app similar to a simulated bedside alarm clock that's "always on," etc.
Thanks in advance.
Those 'alarms' are Local Notifications, and are very handy. They're fired even when an application is closed, and even when the device is asleep.
The concept of asleep is not too tricky; when the user 'quits' your application (pressing the home button), your application will either be halted and placed into a frozen state (4.x), or quit entirely (3.x). Nonetheless, you are given the opportunity to do a few cleanup operations before the latter happens with the - (void)applicationWillTerminate:(UIApplication *)application method, and before the former happens with the - (void)applicationDidEnterBackground:(UIApplication *)application method (both are called upon your delegate class).
The concept of 'sleep' means that in both iPhone OS 3 and iOS 4 you'll receive the following method when your app loses focus (and also when an SMS comes in, or an alert, etc):
- (void)applicationWillResignActive:(UIApplication *)application
Really, most applications (with the exceptions of applications that are designed to work in the background, like voip, audio streaming, etc) simply quit on close. But if you need to, you can also suspend the freezing of your app and ask for more time to complete a task.
This was a lot easier to grasp in the 3.x days, but now with 4.x's 'multitasking' it becomes a bit harder. It's not too daunting though, and a read of this will help a bit.
This may be of help:
http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIApplication_Class/Reference/Reference.html
see the applicationState for UIApplicationState.