I am working on iOS app in which i am creating video from images. I am using AVAssetWriter to achieve this. Everything works fine. But When app goes in background and switched back, the video writing fails. AVAssetWriter's finishWritingWithCompletionHandler is not getting called when i switch back to app.
May be duplicate of AVAssetWriter fails when Application enters Background during Rendering , but i am not getting any help from there.
Any idea for this?
Thanks
This answer is based on the assumption that you want the video to continue rendering while in the background.
I fixed this in my app doing by asking the OS to grant the app background task permisions (for a limited amount of time). This answer might help you too
iOS generating a video in the background task
#property (nonatomic,assign) UIBackgroundTaskIdentifier __block backgroundRenderingID;
UIApplication *app = [UIApplication sharedApplication];
_backgroundRenderingID = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:_backgroundRenderingID];
_backgroundRenderingID = UIBackgroundTaskInvalid;
}];
Don't forget to let go once you are done!
[[UIApplication sharedApplication] endBackgroundTask:_backgroundRenderingID];
Related
I am developing an application, in which I am fetching some photos from the XML link using NSXMLParser, so it takes some time to load images into view, while loading if I click on the home button in iPhone (device) and open the application again, the App crashes. I didn't know how to make my app to be able to run also in background state. I googled and found, "App States and Multitasking" but i can't able to make it in my application. Any solutions or links will be appreciated.
Try This
UIBackgroundTaskIdentifier backgroundTask = 0;
UIApplication *application= [UIApplication sharedApplication];
backgroundTask = [application beginBackgroundTaskWithExpirationHandler:^{
[application endBackgroundTask:backgroundTask];
}];
use this code in your application at initial method
- (void)applicationDidEnterBackground:(UIApplication *)application
{
//call your upload method
}
In iOS 5 When Application Enter background wi-fi connection is lost.
But I want to use wi-fi connection for the next 4-5 minutes before the device sleeps as some tasks can be performed within 4-5 minutes of application enter background.
I think this can be accomplished by using beginBackgroundTaskWithExpirationHandler:, but i am not able to solve the problem
just disable iPhone to go to sleep mode
-(void) sleepModeDisable{
[[UIApplication sharedApplication] setIdleTimerDisabled:NO];
[[UIApplication sharedApplication] setIdleTimerDisabled:YES];
}
call this function every 10 second, this might help u
The way I handle this is to use beginBackgroundTaskWithExpirationHandler for every network request I'm sending.
This way I make sure that all my networking will completed even if my app moved to background.
I'm usually using one singleton object to handle all network request, so before the request is sent I call
- (void)startBackgroundTask
{
// ask for extra time if this is called when app go to suspended
UIApplication *application = [UIApplication sharedApplication];
_bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
// Clean up any unfinished task business by marking where you.
// stopped or ending the task outright.
[application endBackgroundTask:_bgTask];
_bgTask = UIBackgroundTaskInvalid;
}];
}
And after I get a response (success/failure) or if I canceled the request, I call
- (void)stopBackgroudTask
{
UIApplication *app = [UIApplication sharedApplication];
if (_bgTask != UIBackgroundTaskInvalid) {
[app endBackgroundTask:_bgTask];
_bgTask = UIBackgroundTaskInvalid;
}
}
* Don't forget to define UIBackgroundTaskIdentifier *_bgTask;
Also if you are planning to make a massive use of Wi-Fi you should set the Application uses Wi-Fi key in your plist file to YES, otherwise your Wi-Fi will be shut done after 30 minutes even if your app is running.
No rocket science here, this is intended behavior in iOS that to save battery the Wi-Fi shuts off when phone is locked UNLESS you tell iOS that your app needs a persistant Wi-Fi, then it wont close it for you when your app is running.
For that just add UIRequiresPersistentWiFi to your info.plist and mark it YES
Documentation
I have implemented Audiostreamer class of Matt Gallagher in my application and it works fine in ios4. But when I switched to iOS5 the background playing is not working in there.
I have added UIBackground Modes and Application does not run in Background plist values to my application. So I think the issue is something else.
it wont work in simulator, you're not in simulator are you?
#j_mcnally iOS5 Simulator supports background playing.
#thoughtbreaker In Matt Gallagher there are some flows. Does your audio not play in the background at all or it stops after one track is finished playing.
If its not playing at all in the background than there may be buffering related problem...
You should use Background expiration handler, in your audioStateChange method, but only when app is in the background.
UIApplication *app = [UIApplication sharedApplication];
UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:nil]
}];
You can check the background mode by setting a global flag in applicationDidEnterBackground method
Also invalidate the handler in your audioStart Playing method
[app endBackgroundTask:bgTask];
we have an app that has a specific purpose where an exit is required. After the exit a process needs to run in the background for a certain amount of time or until finished. We just need to know how to programmatically force the app to enter the background where processes can continue running. Any help on this would be great! Thanks in advance!
UPDATE: We have confirmed that there does not seem to be a programmatic way to force the app to quit / enter background and continue running background tasks. You can force the the app to exit using exit(0); but this kills the app all together. However, the bulk of this question was concerning running tasks in the background. We have found a solution that allows our app to begin processing data and handling tasks that a user has setup to be processed. Here is the code required. This needs to be added to the app delegate and multitasking is required on the device / IOS.
- (void)applicationDidEnterBackground:(UIApplication *)app{
// Check that IOS supports multitasking
if ([[UIDevice currentDevice] respondsToSelector:#selector(isMultitaskingSupported)]){
// Check that the device supports multitasking
if ([[UIDevice currentDevice] isMultitaskingSupported]) {
// Custom setting to allow users the freedom to enable or disable background tasks
BOOL enabled = [[NSUserDefaults standardUserDefaults] boolForKey:#"backgroundTasksEnabled_key"];
if ( enabled ){
//Get the shared application instance
backGroundApp = [UIApplication sharedApplication];
background_task = [backGroundApp beginBackgroundTaskWithExpirationHandler: ^ {
[backGroundApp endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
}];
// Run in background
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSLog(#"\n\nProcess background tasks!\n\n");
// Do your work here
});
}
}
}
}
You can force an iOS app into the background by sending a registered URL to another app to handle, such as a web site URL to Safari.
[[UIApplication sharedApplication] openURL:[NSURL URLWithString: myWebsiteURL ]];
Many many apps that call Safari to handle URLs are approved by Apple.
To get any time in the background, an app has to be appropriately configured using one of the allowed background modes (audio, location or VOIP); or the app can request a few minutes of extra time in the background before being suspended by calling the beginBackgroundTaskWithExpirationHandler method
You can't have a process running (doing work) in the background in iOS, you get a few seconds when the app quits to do any clean up and that's it!
You cannot force an application into the background, I'm fairly sure that Apple's guidelines prohibit you from doing that. What could your app possibly be doing that it can only do in the background and not in the foreground?
I am trying to implement an application for iPhone that should simply download some content out of the web. This download is quite big, so I implemented the download as a background task to give the user the chance to do some other stuff with his phone while downloading. My problem is that if the user pushes the lock button (or if auto lock kicks in) the applicationWillResignActive: in the AppDelegate is called and after about ten seconds the download is aborted because the phone does not enter background and just stays inactive.
My question is what am I doing wrong? How can I ensure that the download is continued, even if the phone is locked?
Thanks in advance.
You need to surround the downloading code with background task block like this:
UIApplication* app = [UIApplication sharedApplication];
UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
//here you need to finish what you are doing evven if you've not finished yet, otherwise your app will be killed
[app endBackgroundTask:bgTask];
}];
//here comes your downloading code
[app endBackgroundTask:bgTask];
This will give you 10 minutes(according to some other posts) to execute code in background...