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!
Related
Is it possible to put your app in the background, and have a counter that once expires, wakes up the app and have the app does some action? I know it's basic, but I just cant seem to have it work. Where do I put this counter + action? Under app did enter background?
Thanks for the help.
I don't think that this works in general:
You are allowed only to run in the background for specific tasks:
Apple doc tells which tasks that are:
One of that tasks is receiving GPS messages.
As long as you have GPS enabled and your app configured that it uses GPS for background, your app stays alive in the background.
If you disable GPS some time later it will suspend, and not wake up till the user activates it.
So to realize your problem you have to stay active in the background (e.g by reading GPS).
You can start the timer in AppDelegate:applicationDidEnterBackground or similar
If you need more time to shutdown, you explicitly can request for more time, there is one method for that. I dont know what happens if you request more at regulary intervals
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Internal clock in iPhone background mode
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 ?
You can't in background mode.
The only way the device knows what time it is is when the user tells it (yes, there's automatic time updates but that can just be turned off)
If you wanted to know the 'actual' tone, you would have to ask an external source (I guess your server) while your app was running.
However, you might be able to keep track of the time by recording the time stamp each time the location is found in the background. Then when your app is started you can compare them all; if they look odd, compensate for the clock change.
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.
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 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