I want to call a post method every 60 seconds later while application is in background mode.My objective is to store user location and send it to my server.So far, for test purpose I have used beginBackgroundTaskWithExpirationHandler and NSTime for every 3 seconds call of a temporary post call and it's working fine. But problem is, this background task is being stopped after 10 times call. but I want it to call it indefinite times in certain interval(suppose every 60s or once in a day).
Application iOS Deployment target : 9.0 and its Objective C project with swift compatibility. So far I have done this:
- (void)applicationWillResignActive:(UIApplication *)application {
self.backgroundUpdateTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
[self endBackgroundUpdateTask];
}];
}
- (void) endBackgroundUpdateTask
{
[[UIApplication sharedApplication] endBackgroundTask: self.backgroundUpdateTask];
self.backgroundUpdateTask = UIBackgroundTaskInvalid;
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
[self endBackgroundUpdateTask];
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
[NSTimer scheduledTimerWithTimeInterval:3.0 repeats:YES block:^(NSTimer * _Nonnull timer) {
[self targetMethod];
}];
}
can anyone help me out how can I call this targetMethod in regular interval?
Thanks
Related
I'm developing an application that uses a background task to keep tracking of the user position every 20 seconds. All is fine, except that when I enter the application in background, a new background tasks is created, so that I can have in final multiple background tasks that are running.
I tried to add [[UIApplication sharedApplication] endBackgroundTask:bgTask]; in applicationWillEnterForeground, but that do nothing.
The point is that I want to invalidate/disable all running background tasks when I enter the app and create a new one when I enter in background, or to keep a just one background task running.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
[self runBackgroundTask:10];
}
-(void)runBackgroundTask: (int) time{
//check if application is in background mode
if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
__block UIBackgroundTaskIdentifier bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
[[UIApplication sharedApplication] endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:#selector(startTracking) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] run];
});
}
}
-(void)startTracking{
//Location manager code that is running well
}
I would suggest changing UIBackgroundTaskIdentifier to be a property of the app delegate class and initialize it to UIBackgroundTaskInvalid in didFinishLaunchingWithOptions. Then, in your other app delegate methods, you can just check the value of this property to determine whether there is a background task identifier to end or not.
--
An unrelated observation, but you don't need that runloop stuff. Just schedule the timer on the main thread/runloop (with scheduledTimerWithTimeInterval) and get rid of all of that runloop stuff (because you already added it to the main runloop and that runloop is already running).
For example, let's assume I wanted to do something every 10 seconds while the app was in background, I'd do something like the following:
#interface AppDelegate ()
#property (atomic) UIBackgroundTaskIdentifier bgTask;
#property (nonatomic, weak) NSTimer *timer;
#end
#implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.bgTask = UIBackgroundTaskInvalid;
return YES;
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
self.bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
if (self.bgTask != UIBackgroundTaskInvalid) {
[[UIApplication sharedApplication] endBackgroundTask:self.bgTask];
self.bgTask = UIBackgroundTaskInvalid;
}
}];
self.timer = [NSTimer scheduledTimerWithTimeInterval:10 target:self selector:#selector(startTracking) userInfo:nil repeats:YES];
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
// invalidate the timer if still running
[self.timer invalidate];
// end the background task if still present
if (self.bgTask != UIBackgroundTaskInvalid) {
[[UIApplication sharedApplication] endBackgroundTask:self.bgTask];
self.bgTask = UIBackgroundTaskInvalid;
}
}
- (void)startTracking{
NSLog(#"%s", __PRETTY_FUNCTION__);
}
Now, in your code sample, the timer wasn't a repeating timer, so if you only wanted to fire the timer once, then set repeats to NO, but then make sure that startTracking then ended the background task (no point in keeping the app alive if you're not going to do anything else).
BTW, make sure you run this code on a device, and do not run it from Xcode (as being attached to Xcode changes the background behavior of apps).
Specify location background mode
Use an NSTimer in the background by using UIApplication:beginBackgroundTaskWithExpirationHandler:
In case n is smaller than UIApplication:backgroundTimeRemaining ,it will work just fine, in case n is larger, the location manager should be enabled (and disabled) again before there is no time remaining to avoid the background task being killed.
This does work since location is one of the three allowed types of background execution.
Note: Did loose some time by testing this in the simulator where it doesn't work, works fine on phone.
I am trying to get this to work correctly but it always seems to end early at 174 seconds (2.9 mins). I been following every tutorial possible online on how to use beginBackgroundTaskWithExpirationHandler and I don't see anything wrong with my code. I need this to end at 8.5 mins. The endBackgroundTask method doesn't even gets call before the expiration handler gets called. Is anything wrong with this?
- (void)applicationDidEnterBackground:(UIApplication *)application {
if([[UIDevice currentDevice] respondsToSelector:#selector(isMultitaskingSupported)])
{
NSLog(#"Multitasking Supported");
backgroundTask = [application beginBackgroundTaskWithExpirationHandler:^ {
NSLog(#"Terminated");
//Clean up code. Tell the system that we are done.
[application endBackgroundTask: backgroundTask];
backgroundTask = UIBackgroundTaskInvalid;
}];
timer = [NSTimer scheduledTimerWithTimeInterval:1
target:self
selector:#selector(count:)
userInfo:nil
repeats:YES];
}
else
{
NSLog(#"Multitasking Not Supported");
}
}
-(void)turnOffDesktops:(NSTimer *)time {
//do smth
if(count < (60*8.5)){
NSLog(#"%d",count);
count++;
}else{
[application endBackgroundTask: backgroundTask];
backgroundTask = UIBackgroundTaskInvalid;
[timer invalidate];
timer = nil;
count = 0;
}
}
There has never been a commitment from Apple on how long you would be allowed to perform your background tasks. Historically (until iOS7), apps were given usually 10 minutes to run in the background. This is no longer the case! Watch the WWDC 2013 video on backgrounding. With the addition of the new download & upload API in NSURLSession (ability to schedule download and upload tasks on an external dedicated daemon), Apple has reduced the allowed background time significantly. They've done this because this API has always been meant for download and upload, not arbitrary tasks in the background.
You can determine the amount of time left in background by querying - [UIApplication backgroundTimeRemaining]. You can use this to schedule your code to start at the latest possible.
I would like to trigger action after some ammount of time (in production that will be 30 minutes) and right now I'm using NSTimers scheduledTimerWithTimeInterval. During tests (with timeout being 20 seconds, not 1800 seconds) everything seems fine. In debbuging mode (running from XCode) everything seems fine as well, because the device does not autolock. But in real life, when application is ran on device, autolocking (precisely autolocking, triggering lock button does not) "freezes" the timer (or at least moves the timer trigger somehow to future).
Can I handle that situation? Of course I can disable idleTimer in UIApplication sharedApplication but when application will enter background mode ipad still can autolock.
Actually you can,
First of all, create a default value for "startTimeOfMyExoticTimer" to NSUserDefaults:
[[[NSUserDefaults] standardDefaults] setObject:[NSDate date] forKey:#"startTimeOfMyExoticTimer"];
Then kick of a timer to check if the valid time range is over:
[NSTimer scheduledTimerWithTimeInterval:0.1f target:self selector:#selector(checkIfTimeIsOver) userInfo:nil repeats:YES];
Then implement your checker method:
-(void)checkIfTimeIsOver{
NSDate * now = [NSDate date];
NSDate * startTime = [[NSUserDefaults standardDefaults] objectForKey:#"startTimeOfMyExoticTimer"];
// Here compare your now and startTime objects. (subsract them) and see the difference between them. If your time range is to be set on 30 seconds. Then you should check if the time difference between those objects are bigger than 30 seconds.
}
This will be working even if the device is locked, the app is in background etc.
This approach worked for me, hope it'll work for you too
//Implement this block help your application run background about 10 minutes
#interface AppDeledate(){
UIBackgroundTaskIdentifier backgroundTaskId;
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// if missing interval exist > start timer again and set missing interval to 0
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
NSLog(#"Did Enter Background");
backgroundTaskId = [application beginBackgroundTaskWithExpirationHandler:^{
NSLog(#"Background Task Expired !!!\n");
[application endBackgroundTask:backgroundTaskId];
backgroundTaskId = UIBackgroundTaskInvalid;
//save missing interval to NSUserDefault
}];
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
NSLog(#"Will Enter Foreground");
if (backgroundTaskId && backgroundTaskId != UIBackgroundTaskInvalid) {
[application endBackgroundTask:backgroundTaskId];
backgroundTaskId = UIBackgroundTaskInvalid;
}
}
I am using a serial dispatch queue to serialize some network requests when the user moves the app to the background.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
dispatch_queue_t opQ = dispatch_queue_create("com.myapp.network", NULL);
dispatch_async(opQ, ^{
[self sendNetworkData1];
[self sendNetworkData2];
[self sendNetworkData3];
});
}
The problem is that when they run on this queue I have created, the app doesn't stay active even for the 5 seconds it is supposed to.
On the contrary, when I send the same requests outside of a queue, they are being sent for approximately 8 sec. but the app crashes afterwards.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
[self sendNetworkData1];
[self sendNetworkData2];
[self sendNetworkData3];
}
I would also like to write the remaining ones on the disk, so that they can be sent the next time the user opens the app.
What's the best way to implement this?
When the application enters the background if it requires additional time to complete some task you will want to notify the OS of that. The detailed documentation is here: http://developer.apple.com/library/ios/#DOCUMENTATION/iPhone/Conceptual/iPhoneOSProgrammingGuide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html. Here's a quick and dirty patch.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
__block UIBackgroundTaskIdentifier backgroundTask; //Create a task object
backgroundTask = [application beginBackgroundTaskWithExpirationHandler: ^ {
[application endBackgroundTask:background_task];
backgroundTask = UIBackgroundTaskInvalid; //Set the task to be invalid
}];
dispatch_queue_t opQ = dispatch_queue_create("com.myapp.network", NULL);
dispatch_async(opQ, ^{
[self sendNetworkData1];
[self sendNetworkData2];
[self sendNetworkData3];
[application endBackgroundTask:background_task];
backgroundTask = UIBackgroundTaskInvalid; //Set the task to be invalid
});
}
The bottom line is that you notify that the application needs to run in the background with beginBackgroundTaskWithExpirationHandler: THen when your done you call endBackgroundTask: to notify the OS that you are finished processing in the background. And finally make sure that you reset the backgroundTask variable to UIBackgroundTaskInvalid.
I am trying to do two things for a simple test app.
I am stuck at trying to learn how to use beginBackgroundTaskWithExpirationHandler
I want to execute a backgroundTask when the user presses the home button (nothing fancy). In 9 minutes, I'd like to alert the user that the time is about to expire (if possible) and allow the user to switch back into the app to renew the 10 minutes.
I don't need backward compatibility with iOS 3, or 4.
If you want your code to continue in the background, then you'll need to wrap it in a background task. It's also very important that you call endBackgroundTask when you're finished - otherwise the app will be killed after it's allotted time has expired
- (IBAction) buttonPressed: (id) sender
[self beingBackgroundUpdateTask];
// Do your long running background thing here
[self endBackgroundUpdateTask];
});
}
- (void) beingBackgroundUpdateTask
{
self.backgroundUpdateTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
[self endBackgroundUpdateTask];
}];
}
- (void) endBackgroundUpdateTask
{
[[UIApplication sharedApplication] endBackgroundTask: self.backgroundUpdateTask];
self.backgroundUpdateTask = UIBackgroundTaskInvalid;
}
Put the code in the applicationDidEnterBackground function in your UIApplicationDelegate. You will need to set up a UILocalNotification and schedule it. You should also probably disable it in applicationWillEnterForeground so it doesn't fire off the user goes back to the app before it expires.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
UILocalNotification *timerNotification = [[UILocalNotification alloc] init];
//set up notification with proper time and attributes
[[UIApplication sharedApplication] scheduleLocalNotification:timerNotification];
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[UIApplication sharedApplication] cancelAllLocalNotifications];
}
The cancelling code I gave there will actually cancel all notifications. If you have multiple notifications and only want to cancel a specific one, you should give the userInfo property of your notification a key/value when you set it up. Then, when the application enters the foreground, get the list of all active notifications by doing
NSArray *notifications = [[UIApplication sharedApplication] scheduledLocalNotifications];
and loop through them, checking userInfo until you get to the one you want and then just cancelling that one with
[[UIApplication sharedApplication] cancelLocalNotification:whateverNotification];