Sorry if it is such a dumb question or if I'm not ninja google-ing enough. I just need the answer quick.
I have an external accessory which gets data from ANT+ sensors. My question is, would it be possible that my application using the external accessory continue to run in the background, or at least send push notifications?
Thanks and feel free to downvote because I think it's very lazy of me to ask here.
According to the Apple specs your application won't receive events immediately while in the back ground but all events should be hold in a queue and sent when back foreground. Depending on the frequency your device is running and the elapsed time while staying in the background you should be prepared to get a bunch of events.
See External Accessory Programming Topics: Monitoring Accessory-Related Events
and Multitasking Support for more information.
Related
I am working on a medical related app where a medical device interfaces via bluetooth with an iphone. However I cannot figure out how to allow the app to run indefinately in the background. Right now it only communicates when the app is open. I have been reading a lot of questions related to this and I haven't managed to find an answer which fits. I'm sorry if this is a duplicate. Can someone point me in the direction of how to implement this.
ETA - I just got confirmation that this is supposed to be able to go on the App Store.
Did you come across this question: Background time issue for Bluetooth LE app for Iphone 4s
It seems that adding the background mode bluetooth-central (see documentation) can enable your app to run in the background while handling bluetooth events. As noted in the question above though, you could always set background mode to audio and play a blank looping audio track to keep your app alive and responding if you don't need to be on the App Store.
I know this question may be a little bit common and over asked but I cannot find any precise information... so :
Is it possible to have some kind of thread running when the app is in background so I can perform basic sync with my webservice ?
App is in background : I mean the user clicked the Home button, or switched to another app
basic sync : photo upload and download with AFNetworking. I know it has method to continue an HTTPRequest while app is in background, but this is not my point.
My goal would be to make some kind of sync manager, reading a list of photos to update created while the user was on the app, and perform those changes.
I know that the manager could be killed by the OS, but since my server uses atomic transfers it is not a problem. I just need a way to relaunch it... Push ?
I think apps like Google Latitude or Mail and those kind of apps uses what I am looking for but I cannot find any relevant details on it. And using iOS5 is not a problem but waiting for iOS6 would not be a solution.
Thank you for your replies !
PS : well I almost forgot. the app is designed for an enterprise program, so maybe rules are different ? I don't think there is any check for in-house deployment so it might lead to new possibilities...
Apple's Mail client has a background daemon which keeps it running but you can't have that with your own applications. Once an app enters a background state, it must halt it's operations. You can request for a little more time when backgrounded to finish off any transfers or writes to disk (see the Executing a Finite-Length Task in the Background section on Apple's Multitasking Guide)
Google Latitude has events generated based on location. This is a special type of backgrounding introduced by Apple for certain types of applications (see Implementing Long-Running Background Tasks section on Apple's Multitasking Guide) but this can't be used for HTTP syncing. It can only be used for audio, location, voip, newstand content, bluetooth and external hardware attachments.
Push doesn't seem like a solution because it only generates an alert. It doesn't trigger any action until the user triggers the opening of the notification.
You'll want to read Tech Note 2277 Networking and Multitasking.
Basically you have a couple of options:
If you can convince Apple that your app is a VoIP app then you can register a VoIP socket and the OS will resume your background app whenever there is activity on that socket.
Your main option though is to register a background task for any outstanding activity that you have to do when your app is put in the background. You typically get 10 minutes to finish up that work.
Mail is a special app with privileges you don't get.
Apps like Latitude typically register themselves for location updates, specifically to be woken up when there are major geo-position changes. Apps that record GPS tracks do similar things.
Found it !
Using Suhail Patel 's link on Apple's Multitasking Guide I added the voip tag to UIBackgroundModes in Info.plist and use setKeepAliveTimeout:handler: method of UIApplication to relaunch it if needed once the app is going to sleep.
I hope this will help a lot of you !
Of course this app won't be allowed to be on the App Store but for in house development this is in my opinion the best way to do so.
Thanks everyone for showing me the right direction !
when we press on the Home button two times then we see the all the apps running in the background.if no apps is running in the background then there are only two controls by default.So my question is can we add same functionality in our app? means i want to add some more controls on the background. if yes then how?
You cannot add background functionality to your app.
The only ways an application can be controlled in the background are via:
Audio events. Your app registers and audio session and the user can press play/pause, next, and previous on the lock screen, task bar, or remote headphones. Unless you're doing audio-specific programming, however, you shouldn't use this.
Push notifications. Your app receives messages from a remote server via Apple's APN, triggered by one of your servers - maybe by a website application.
Sensor listening. It's possible to have your application process in the background inputs from hardware sensors, such as the accelerometer, compass, or GPS. However, this kills battery life and is discouraged unless it is absolutely necessary.
So to answer your question, no.
I am trying to take advantage of iPhone 4 multitasking feature. I want to run app in background and frequently send http request to send/receive data, is it possible?
Surprisingly, there is actually very little time-slicing going on in the "multi-tasking" iOS 4.x. What goes on instead is really just application suspend / resume. When an application is sent to the background upon the user tapping the home button, it will stop getting execute cycles after a short while (*).
(*) There are a few exceptions. Applications which declare themselves as "VoIP providers", location-based apps, and music apps can get background execute cycles, presumably only though to perform those very specific operations in response to corresponding events (like a "significant change in location" occurring). Some apps apparently try to stretch the rules and find undocumented or not-strongly-documented techniques to continue getting background execute cycles.
And the "requested running time" that Undeadlegion mentioned is limited in duration.
The reality is that on iOS4, applications are not allowed to run continuously in the background.
#Undeadlegion has suggested a plausible way to achieve your goal. To be more clear, take a look at my previous answer to a similar question at SO, iphone - Connecting to server in background
It is possible to request running time while your app is backgrounded.
See Multitasking Developer's Guide
Although, depending on the intent of your http requests, push notifications may be a viable alternative.
This may be necessary because you aren't providing audio, voip, or location services, so your app can't run in the background indefinitely.
Background: Workout App is designed to have a continuous timeline that I can then input what exercise and reps I'm doing in real-time, then graph the results in real-time.
Issue: When the iphone sleeps for too long, we lose the continuity of the Timeline and it restarts. We haven't figured out how to keep the timeline updating while the App is sleeping. I've asked him to do a call to the Iphone internal clock and do the math on where the viewer should be and move them to that point on the timeline. However, he can't figure out how to do this.
Solutions: Have you folks heard of anyways to do this call to the internal clock? Perhaps a better question, can you think of another way around the problem in general?
You could try CACurrentMediaTime which returns mach_absolute_time in seconds. This should be accurate across sleep.
There is no certain way that can assure you app will be running in the background for ever. (If this is what you need)
Even Steve said is Multitasking, iPhone resources are very limited and this means that your app will might be killed while it is in the background without any kind of notification.
(Except by the notification you get when entering the background)
The best thing you can do is low your resource usage. (release as many objects as possible)
Because when the system needs memory it will start killing apps in the background starting by the app that uses more resources.
If you are implementing streaming protocols then is different.
Hope this helps