I have a location based iOS app and I want to interact with a server every x minutes.
I read this post: Send Data Every 10 minutes
But I have to send an empty header to my server even if there is no location update for a while because I have to read any pending commands from my server and it only writes back if you write first.
This has to work even if the app is running background.
What should be the best way to perform this? Using a timer?
I've already made this kind of stuff on Android but I'm a little stuck on how to do here.
Cheers,
Thierry
You can use a NSTimer when the app is running, but you can't do that when the app is in background. The iOS reference contains all the possible uses of multitasking: link
As you can see, there's a small amount of possible operations (voip, audio or location) that are able to wake up your app.
Related
I need to have the following things to work while my iphone application is in the background mode.
1.Run a clock.
2.Communicate with the server every 15 mins to get the server time and one another value.
3.Need to start downloading data in background mode.
I searched a lot whether these are possible or not. Kindly give confirmation on these.
I am developing an iPhone application which involves Ticket Booking System. I registered my application as location based beacuse it is using user's location taken in background for a purpose.
My problem is that i need to run an internal clock in my application in background mode. I need to write the codes for internal clock in core location delegate methods, so that internal clock will also run along with the location bsed services. Will my app get rejected? Is anything wrong in doing like this?
I need to get the correct time to use in my app, so that i am running this internal clock. I can use NSDate, but that will return the device time. Anyone can change the device time. So once somebody chaged, wrong time will affect the smooth functioning of the app. Kindly some body suggest to get the correct time with out running the internal clock ?
I suppose you want to do this with your app not running in the foreground - and that is not possible, if you don't use some tricks like playing an empty audio file and pretending to be a music player or the like.
In iOS, you can only execute code of your app while it is actively running in the foreground, except for some specific tasks like VOIP or music playing.
If you want to do this while your app is running in the foreground, just use NSTimer and a background process for loading, like it was suggested. But then you should also prevent the iPhone from entering SLEEP mode after 1 minute, otherwise it won't work when th euser is not actively using the app during the 15 minutes ...
This is possible, what you need to do is,
1] Run a background thread, in which set a NSTimer with 15mins.
2] Set repeat:YES to call it at every 15mins.
3] And start download your need there!
I will do like this if I stuck like your situation!
I need that my app will send some data to server every six hours for example. Purpose is that it will send request to server even when app in background. As I know only thinks GPS, Music, Push Notifications work on background. Also, as I know UIApplication method beginBackgroundTaskWithExpirationHandler: works not for a long time after app goes on background. Guys, anybody have idea how to implement this? Thanks a lot!
It's simply not possible within the limits of the current iOS SDK. The only kind of apps that can update their content regularly from the background are Newsstand apps and for them, the interval is 24 hours AFAIK and the entire updating process is largely triggered by Apple.
Unless your app falls into one of the categories you mention, the short answer is you can't. The only exception is for Newsstand apps.
But: what data would you be sending to the server if your app isn't running? If you send data to the server when something happens then the server will always be up-to-date. If the user isn't running the app then, by definition, nothing has happened and the server is still "in sync" with the client. (Yes, this potentially makes the server harder to code.)
I'm creating an app which connects to server and sends some text.
If network (both wifi or 3g) is there, it will immediately send the text to server.
But if there is no network, it keeps on polling for server connection every 5 minutes.
All this part is working fine.
But when using iPhone 4 device, i want the app to check for server connection even when app goes into background. So, when app goes to background and when network comes back, it must be able to send the text to server.
How can I achieve it? I've seen some apps where they say that the app will upload photos to server even in background. How will they do it?
I suggest you read this article from Apple carefully, especially the Completing a Finite Length Task in the Background section.
http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/BackgroundExecution/BackgroundExecution.html
Something to clarify:
Once your app is in the background and is frozen by the OS, there would be no way for your app by it self to wake up and re-connect to the internet.
However, according to the article above from Apple, you can call this beginBackgroundTaskWithExpirationHandler method from your app's delegate to apply for additional time when put in the background, which is to say, though your app cannot wake up by it self when in background, it can, when in the background and not frozen, try to apply for additional time to finish its lengthy task.
Hope it helps.
There is a trick that I think flayvr is using.
If you download and use the app, you will see that they require you to enable your location.
And why is that?
because they want like you to do something in the background even when the app is terminated (they creating an album out of your newly captured photos), and how do they do that?
They use the significant location change, where when someone is traveling some significant distance (something like 500m) each app that registered for significant location change will get awaken for a limited amount of time to perform some quick task and will be terminated in a few seconds.
So your app can register to that event also and when the event of significant location change fired you will be able to send the text to server (quickly).
Hope that helps.
Until now you can do that on iOS7 with Background Fetch.
Take a look at this article.
However you only have up to 30s to get the task done.
According to the article above, there's also another solution called Background transfer service.
If more time is required though, then the Background Transfer Service
API can be used
Create a new project in Xcode and you will see there are bunch of new methods auto generated in app delegate file. like applicationDidEnterBackground, applicationWillEnterForeground etc.
read the description you have to call your thread to upload data on server here.
I need to develop an enterprise app that monitors the network traffic. Basically it detects if the user is in wi-fi or cellular data and save the amount of bytes was sent and received in a period of time.
I saw an App at the AppStore that do exactly this job.
Detecting wi-fi or cellular data is quite simple using the Reachability Sample provided by Apple.
My problem is to keep monitoring the bytes sent and received while the app is in background.
As it is an enterprise App, I used UIBackgroundModes "voip" to avoid the app to be terminated.
I also installed the setKeepAliveTimeout method and I'm able to see the logs each 10 minutes, BUT only for 10 seconds after the method runs. I mean, setKeepAliveTimeout brings my App to run a Timer for 10 seconds each 1o minutes.
I'm thinking wether or not a task in background is the best solution for my problem.
I'll appreciate any comments.
EDIT: Ok guys. Thats the perfect way to do it.
First of all you must read this:
http://www.christian-fries.de/blog/files/tag-ios.html
I tried this and it works really fine.
All we need to do is to create a second thread detached from the main one. This way we have a continuos threading running forever. You must see the GCD docs at Apple's website also.
Second thing you should consider for an enterprise App is to set it up as a voip App, this way iOS will put your App running even after a reboot. It's a special behavior iOS has to keep voip Apps running.
Thats it guys.
I hope it can help you.
We dont have access to this data. There is no way to measure traffic.
The app you saw made an estimation (eg. 1mb/min) and after applicationWillEnterForeground. then you calc time x estimated-traffic and there we go.
Unfortunately there is no way to measure,
so I did a traffic-reset in settings and then i streamed exactly 1 min music. after a few repetitions I had my results. The problem is, that this works only fine with static traffic-processes like audio or video.
hope could help
endo
EDIT: look answer below!
I need to write an application, that every 10 minutes it should be awaken from suspended mode, get user location via gps and send this information to the server by network.
Depending on the response it should return to the suspended mode or show local notification to the user.
Is there a way to do this on iOS 4?
I've tried different approaches, but the only working for me was to start monitoring user location in backgroind and declare the application as location background application. In that case it worked in background and has a network connection. But this approach takes a lot of power and not accepted cause application should work 24/7.
May be there is a way to write some daemon that should work in background and wake my application every 10 minutes?
Apparently, Pastebot tried to do something similar with the 'audio' multitasking declaration (by playing a silent audiofile) and got rejected.. UNTIL they actually presented a option to the user to pick which audiofile they wanted to play. It's in the appstore now. :)
In this case: What is your reason for not wanting to use the location updates? If battery-usage is a concern, you can use the 'significant location changes only' option, after which you can temporarily change to a more accurate option.
This isn't possible outside of the method you have already tried.
The iPhone background task API will allow you to run a location service in the background.
There is no way to write daemons for the iPhone without jailbreaking, and that is not something I'm able/prepared to help you with.
App store friendly: use new APIs in iOS4, which allows u to make use of GPS location
Anti App store: create a daemon by adding a specific plist file to System/Library/LaunchDaemons/ and put ur app under Applications/. this approach requires a jailbroken iPhone however...
detailed information plz google the following keywords: daemon, multitask, background, etc...
cheers, Lloyd