iPhone timer task for long processes - iphone

Question

When the application enters into background state, the time used to run in background is not working. Following is the code.
In AppDelegate.h,
#interface AppDelegate : UIResponder <UIApplicationDelegate>
{
BOOL status;
UIBackgroundTaskIdentifier bgTask;
}
In AppDelegate.m
- (void)applicationDidEnterBackground:(UIApplication *)application
{
NSAssert(self->bgTask == UIBackgroundTaskInvalid, nil);
bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
dispatch_async(dispatch_get_main_queue(), ^{
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}];
dispatch_async(dispatch_get_main_queue(), ^{
if ([application backgroundTimeRemaining] > 1.0) {
// Start background service synchronously
[[vController getInstance] run];
}
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
NSAssert(self->bgTask == UIBackgroundTaskInvalid, nil);
bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
dispatch_async(dispatch_get_main_queue(), ^{
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}];
dispatch_async(dispatch_get_main_queue(), ^{
if ([application backgroundTimeRemaining] > 1.0) {
// Start background service synchronously
[[vController getInstance] stopbackground];
}
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}
And in view Controller.h,
#interface vController : UIViewController <AVAudioPlayerDelegate>
-(void) run;
-(void) stopbackground;
-(void) getMessage:(NSTimer*)theTimer;;
+(vController*) getInstance;
#property (nonatomic,retain) NSTimer * timer;
#end
the view controller.m,
#implementation vController
#synthesize timer;
vController *tvc;
- (void)viewDidLoad
{
[super viewDidLoad];
tvc = self;
// Do any additional setup after loading the view, typically from a nib.
}
+ (vController*) getInstance
{
return tvc;
}
- (void)stopbackground
{
timer = [NSTimer scheduledTimerWithTimeInterval:15.0 target:self selector:#selector(getMessage:) userInfo:nil repeats:YES];
}
- (void)run
{
timer = [NSTimer scheduledTimerWithTimeInterval:15.0 target:self selector:#selector(getMessage:) userInfo:nil repeats:YES];
}
- (void) getMessage:(NSTimer*) theTimer
{
NSError *error;
NSString *path = [[NSBundle mainBundle] pathForResource:#"alert" ofType:#"mp3"];
AVAudioPlayer* theAudio=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:&error];
if (theAudio == nil) {
NSLog(#"%#", [error description]);
}
NSLog(#"Hi");
theAudio.delegate = self;
theAudio.numberOfLoops = 1;
[theAudio play];
}
- (void) dealloc{
[timer release];
[super dealloc];
}
I am using it on simulator 6.0

Answer 1

Depending on your use case, this may not be possible. Namely, Apple does not let you execute code in the 'background' unless you are performing one of the following tasks:
Apps that play audible content to the user while in the background,
such as a music player app
Apps that keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Newsstand apps that need to download and process new content
Apps that receive regular updates from external accessories
Read more at :http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html

Answer 2

By Creating Instance you can Run Background Task in Any View-controller like Below:
// Declare the following in YourViewController.h file.
+ (YourViewController *)getInstance;
- (void)run;
-(void)stopbackground;
// Define the Vollowing in YourViewController.m file.
static YourViewController *instance = NULL;
+(YourViewController *)getInstance {
#synchronized(self) {
if (instance == NULL) {
instance = [[self alloc] init];
}
}
return instance;
}
- (void)run
{
// strat Back ground task
}
-(void)stopbackground
{
// Stop Background task
}
in AppDelegate.h file Declare the Following
UIBackgroundTaskIdentifier bgTask;
in AppDelegate.m file use the Following Methods.
- (void)applicationDidEnterBackground:(UIApplication *)application {
NSLog(#"Application entered background state.");
// bgTask is instance variable
NSAssert(self->bgTask == UIBackgroundTaskInvalid, nil);
bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
dispatch_async(dispatch_get_main_queue(), ^{
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}];
dispatch_async(dispatch_get_main_queue(), ^{
if ([application backgroundTimeRemaining] > 1.0) {
// Start background service synchronously
[[YourViewController getInstance] run];
}
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
NSLog(#"Application entered background state.");
// bgTask is instance variable
NSAssert(self->bgTask == UIBackgroundTaskInvalid, nil);
bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
dispatch_async(dispatch_get_main_queue(), ^{
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
}];
dispatch_async(dispatch_get_main_queue(), ^{
if ([application backgroundTimeRemaining] > 1.0) {
// Start background service synchronously
[[YourViewController getInstance] stopbackground];
}
[application endBackgroundTask:self->bgTask];
self->bgTask = UIBackgroundTaskInvalid;
});
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}