Hi I want to run my app in background until I quit it.For that I have used the code below
bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
dispatch_async(dispatch_get_main_queue(), ^{
[application endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
});
}];
but it quits after particular time.Can any one guide me to achieve this.
You don't!
Apple will allow you to complete a lengthy operation, but it is not ment to keep your app running. This will drain your battery.
There are three kind of background running apps support by Apple: Audio player, VOIP client and location based apps. Location based apps will only receive major location updates and only one audio player can run at a time.
Mis use of the background mode will get you app rejected.
wont work this way. your application need to support one of the background modes in a proper way
Related
I am trying to run image uploading using soap based web service and doing this i face 2 key issue in my app.
Issue 1:- When app uploading multiple images to server and at that time if my application goes in background state than at that time my is stop executing (application suspended state). when i my app goes back from background to foreground state than it again resume my background thread.
Issue 2:- When i try to upload 160-170 images on server from device gallery. i received memory warning after uploading 60-70 images on server. i handle that method and try to free some memory within application and i again start my thread at that time my application crashed. //->> for 2nd issue i add 3 different web service and its too long code so i am not going to share it here. when i check on instrument it generally run on max 2 to 2.5 MB in live bytes but when i uploading thread start it gradually increasing and at some pick point i received received memory warning. my code contains feature of ARC but still i got memory warning issue.
code for issue 1:-
- (void)applicationDidEnterBackground:(UIApplication *)application
{
UIDevice* device = [UIDevice currentDevice];
BOOL backgroundSupported = NO;
if ([device respondsToSelector:#selector(isMultitaskingSupported)])
{
backgroundSupported = device.multitaskingSupported;
}
//NSLog(#"backgroundSupported: %d", backgroundSupported);
if (backgroundSupported)
{
_IsBackground = TRUE;
UIApplication* app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:
^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
// Start the long-running task and return immediately.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0),
^{
while (_IsBackground)
{
//// it contineous run my application within this state.
}
NSLog(#"Background loop ended");
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
});
}
}
1 )
Apple cares very much about battery life on iPhones and iPads, so they are very strict about what can run in the background (which is to say, not too much).
With the current shipping versions of iOS, you only have about 5 seconds to clean up or properly suspend things when your application receives a call to the "applicationDidEnterBackground:" delegate method.
You need to come up with a way to upload your images via a background thread while your app is in the foreground. That means that the only time you can upload images is while your app is visible to the user.
More information can be found in this closely related question.
2 )
For your second issue, it's pretty clear that you are not properly releasing (or setting to "nil", or resetting) some variables that are being used in the process of uploading multiple images, which is why you see memory usage increasing and increasing and eventually killing your app.
You already know about Instruments, but it sounds like you need to get even more familiar with tracking down memory usage and which things in memory are taking up more and more space.
I have an application that uses location services in the background. Works fine.
But what I want to do, at a certain point, is to check some audio levels while the application is in the background. For some reason it doesn't seem to work. When running in foreground, the function works fine, but when in the back ground, the audio recorder average and peak input is always -120..
This is what I use to do the trick (that doesn't seem to work apparently..)
....
[recorder record];
if (levelTimer == nil) {
bgTask = 0;
app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
}];
levelTimer = [NSTimer scheduledTimerWithTimeInterval: 0.02 target: self selector: #selector(levelTimerCallback:) userInfo: nil repeats: YES];
}
...
And yes, the levelTimerCallback is called every 0.02 seconds, even when in the background, so I assume that the beginBackgroundTaskWithExpirationHandler works fine.
Any thoughts or some hints?
Currently, the only supported way to record in the background on an iOS device is to include audio for the UIBackgroundModes key in the app's plist, enable an appropriate Audio Session for recording, and start recording (or playing) audio before the app goes into the background.
If the app uses the Audio Queues or the RemoteIO Audio Unit API for recording, the buffer callbacks can just throw away all the audio buffers until the time of interest, and then compute the energy represented by the PCM samples for the amount of time required when needed.
I dont think iPhone will allow recording in the background. Only few services are allowed when the app goes into background. Logically if your app stays into background for a long time it would then consume a lot of battery as well as buffer to store audio, unless you have time and memory managed these resources. This would also pose issues for your app when you submit it to the App Store.
Although you can refer to this link for knowing what can be run in the background.
I hope this might help u clear things in a way.
iPhone : Running services in the background
Good Luck!!!
There is an app I know of that has background recording. Beatmaker 2. You need to turn run in the background on in the settings of device under beatmaker 2. In beatmaker create an audio track and start recording. Them use the home button on device to exit app but its still recording. You can get creative with different interfaces as well. I do this to feed the iPhone 4 line out into an audio track in beatmaker 2. You can record the audio of anything playing in the foreground. (YouTube videos apps music from your iTunes library. You can edit the waves also after recorded.
I don't mind using private API's or anything of the kind that Apple doesn't like, but would prefer a quick solution that doesn't stuff like playing silence in the background or swizzling.
Obviously this isn't for the app store so please no lecturing :)
So how do you run in the background without any restrictions like "backgrounder"? I didn't manage to find an answer besides some that point people to different directions, but maybe since then someone managed to dig it up already.
Update:
This solution no longer appears to be sufficient (~ iOS 7+ or 7.1+). I'm leaving the original answer for historical reference, and in case it helps produce a future solution based on this obsolete one:
It depends on what you mean by app. If you're talking about a non-graphical background service, then what you want is a Launch Daemon. See here for how to create a launch daemon.
If you have a normal UI application, but when the user presses the home button, you want it to stay awake in the background for an unlimited time, then you can use some undocumented Background Modes in your app's Info.plist file:
<key>UIBackgroundModes</key>
<array>
<string>continuous</string>
<string>unboundedTaskCompletion</string>
</array>
Then, when iOS is ready to put your app into the background (e.g. user presses home button), you can do this, in your app delegate:
#property (nonatomic, assign) UIBackgroundTaskIdentifier bgTask;
- (void)applicationDidEnterBackground:(UIApplication *)application {
// Delay execution of my block for 15 minutes.
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 15 * 60 * NSEC_PER_SEC), dispatch_get_current_queue(), ^{
NSLog(#"I'm still alive!");
});
self.bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
// should never get here under normal circumstances
[application endBackgroundTask: self.bgTask];
self.bgTask = UIBackgroundTaskInvalid;
NSLog(#"I'm going away now ....");
}];
}
Normally, iOS only gives you up to 10 minutes for your UI application to work in the background. With the undocumented background mode, you'll be able to keep alive past that 10 minute limit.
Note: this does not require hooking with MobileSubstrate. If you're using the second method (undocumented Background Modes), then it does require installing your app in /Applications/, not in the normal sandbox area (/var/mobile/Applications/).
Depending on what your "app" is going to do, you can hook MobileSubstrate. This will load with SpringBoard and essentially run "in the background".
If you want to write an actual application, then you can also write a "Dynamic Library" which will be loaded with SpringBoard by MobileSUbstrate. You can talk back and forth between this dylib and your app by using NSNotificationCenter; creating and posting notifications.
I'm developing an app for iOS4. The application is made of two main components, one that is supposed to run in the background and one that is constantly displayed on screen and takes data from the first one. Here's the problem: the first component works just fine until it is put in the background. At that point it stops sending data. Why is that? Is there any workaround?
Thank you.
If you're not using VoIP, Audio or GPS you can only use the task completion mode (which is limited to 10 minutes in background).
To do that you have to tell the OS you want to start a task with:
UIApplication* app = [UIApplication sharedApplication];
UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
and when you're done, you can end it with:
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
Remember that if your running longer than 10 minutes, the OS will kill your app.
In applicationDidEnterBackground: you have the problem that your code still blocks the main thread, which is why it's killed when you exit the app.
If you want to start executing code in applicationDidEnterBackground: you should begin the background task and dispatch whatever it is you want to do with dispatch_async(queue, block_with_your_code);
You can read more on it here
There is non you are only allowed to run VOIP, Audio or Locationbased apps in the background.
So unless you apps falls in one of those categories there is no way to keep you app working in the background.
Apple allows only certain types of apps to run in the background, like navigation and VOIP apps, to name just two. But even those are limited to only the necessary tasks.
The only alternative are "longrunning background tasks" - this allows an app to continue working in the background for up to ten minutes (the exact duration of this "grace period" is subject to change, afaik). You may obvserve this on apps like Hipstamatic, which will finish postproduction on images even when the app is being moved to the background.
As others have pointed out there's no real way to do this, but there is a workaround some apps use. You basically play a track from the users iPod library in the background, which enables your app to stay working in the background for a longer time. You can read more about it on Tapbots' site.
first of all, I know there is only support for voip, audio and location apps to run in background and that they will run just while the audio is been played or while using location services, etc.
What I want to know is if there is a way to keep my app running on background fully operational, doesn't matter the impact on battery's life.
That way the user of my app can select from settings to keep alive the app whenever he wants and just for the amount of time he wish. e.g if he is waiting for something that requires the app to be running, after receiving the messages he can turn off the keep alive functionality.
I don't know if this is possible but I had read some post that say so but unfortunately they didn't say how to =(
UPDATE: In this tutorial, I found that Acrobits has two apps on the Apple Store that "can force the application to stay alive and awake in the background". So there is a way to do this?
From ioS 7 onwards, there are newer ways for apps to run in background. Apple now recognizes that apps have to constantly download and process data constantly.
Here is the new list of all the apps which can run in background.
Apps that play audible content to the user while in the background, such as a music player app
Apps that record audio content while in the background.
Apps that keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Apps that need to download and process new content regularly
Apps that receive regular updates from external accessories
You can declare app's supported background tasks in Info.plist using X Code 5+. For eg. adding UIBackgroundModes key to your app’s Info.plist file and adding a value of 'fetch' to the array allows your app to regularly download and processes small amounts of content from the network. You can do the same in the 'capabilities' tab of Application properties in XCode 5 (attaching a snapshot)
You can find more about this in Apple documentation
You can perform tasks for a limited time after your application is directed to go to the background, but only for the duration provided. Running for longer than this will cause your application to be terminated. See the "Completing a Long-Running Task in the Background" section of the iOS Application Programming Guide for how to go about this.
Others have piggybacked on playing audio in the background as a means of staying alive as a background process, but Apple will only accept such an application if the audio playback is a legitimate function. Item 2.16 on Apple's published review guidelines states:
Multitasking apps may only use
background services for their intended
purposes: VoIP, audio playback,
location, task completion, local
notifications, etc
If any background task runs more than 10 minutes,then the task will be suspended and code block specified with beginBackgroundTaskWithExpirationHandler is called to clean up the task. background remaining time can be checked with [[UIApplication sharedApplication] backgroundTimeRemaining].
Initially when the App is in foreground backgroundTimeRemaining is set to bigger value. When the app goes to background, you can see backgroundTimeRemaining value decreases from 599.XXX ( 1o minutes). once the backgroundTimeRemaining becomes ZERO, the background task will be suspended.
//1)Creating iOS Background Task
__block UIBackgroundTaskIdentifier background_task;
background_task = [application beginBackgroundTaskWithExpirationHandler:^ {
//This code block is execute when the application’s
//remaining background time reaches ZERO.
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
//### background task starts
//#### background task ends
});
//2)Making background task Asynchronous
if([[UIDevice currentDevice] respondsToSelector:#selector(isMultitaskingSupported)])
{
NSLog(#"Multitasking Supported");
__block UIBackgroundTaskIdentifier background_task;
background_task = [application beginBackgroundTaskWithExpirationHandler:^ {
//Clean up code. Tell the system that we are done.
[application endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
}];
**//Putting All together**
//To make the code block asynchronous
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
//### background task starts
NSLog(#"Running in the background\n");
while(TRUE)
{
NSLog(#"Background time Remaining: %f",[[UIApplication sharedApplication] backgroundTimeRemaining]);
[NSThread sleepForTimeInterval:1]; //wait for 1 sec
}
//#### background task ends
//Clean up code. Tell the system that we are done.
[application endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
});
}
else
{
NSLog(#"Multitasking Not Supported");
}
For running on stock iOS devices, make your app an audio player/recorder or a VOIP app, a legitimate one for submitting to the App store, or a fake one if only for your own use.
Even this won't make an app "fully operational" whatever that is, but restricted to limited APIs.
Depends what it does. If your app takes up too much memory, or makes calls to functions/classes it shouldn't, SpringBoard may terminate it. However, it will most likely be rejected by Apple, as it does not follow their 7 background uses.
May be the link will Help bcz u might have to implement the code in Appdelegate in app run in background method ..
Also consult the developer.apple.com site for application class
Here is link for runing app in background