How to keep NSTimer alive in Background on iOS 7?

Question

I have created Application which runs NSTimer in Background. I used the Location manager to run the NSTimer in background,

I used below link to run NSTimer in backgr

Answer 1

-(void)start {

[[NSUserDefaults standardUserDefaults ]setObject:[NSDate date] forKey:@"startTimer"];

 Nstimer*   timer2=[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerFired) userInfo:nil repeats:YES];
}
-(void)timerFired
{
      @try {
    NSDate *timerStartDate = [[NSUserDefaults standardUserDefaults]objectForKey:@"startTimer"];


NSTimeInterval interval=[timerStartDate timeIntervalSinceNow];

int hour1=-interval/3600;

int rem =((int)interval)%3600 ;

int min1 = -rem/60 ;

int sec1 = -rem %60 ;

// NSLog(@"hour %i  rem %i",hour,rem);    
// NSLog(@"hour%i",hour1);
// NSLog(@"min%i",min1);
// NSLog(@"sec%i",sec1);


NSString *strmin=[NSString stringWithFormat:@"%i",min1];
NSString *strhour=[NSString stringWithFormat:@"%i",hour1];

if ([strmin integerValue]<10)
{
    [lblSeconds setText:[NSString stringWithFormat:@"0%@",strmin]];
}
else 
{
    lblSeconds.text=strmin;

}
if ([strhour integerValue]<10) {
    [lblHour setText:[NSString stringWithFormat:@"0%@",strhour]];
}
else
{
    lblHour.text=strhour;

}

}
@catch (NSException *exception) {
    NSLog(@"exception in timer %@ ",[exception description]);

}
  return;   
}

Answer 2

In iOS7, there is a new mode for periodic data fetch. Add the fetch background mode to your app, and in your application delegate, pass an interval to - [UIApplication setMinimumBackgroundFetchInterval:. Your app's delegate will start receiving calls to application:performFetchWithCompletionHandler: once the app is in the background.

More information here: https://developer.apple.com/library/ios/documentation/uikit/reference/UIApplicationDelegate_Protocol/Reference/Reference.html#//apple_ref/occ/intfm/UIApplicationDelegate/application:performFetchWithCompletionHandler:

Answer 3

NSTimer *currentCycleTimer;

UIBackgroundTaskIdentifier bgTask = UIBackgroundTaskInvalid;
UIApplication *app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
}];
[currentCycleTimer invalidate];
currentCycleTimer=nil;
secondsLeft = 120;
currentCycleTimer = [NSTimer scheduledTimerWithTimeInterval: 1.0 target:self        selector:@selector(Countdown) userInfo:nil repeats: YES];

-(void) Countdown
{
  [currentCycleTimer invalidate];
  currentCycleTimer=nil;
}

Answer 4

[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
loop = [NSTimer scheduledTimerWithTimeInterval:0.25 target:self selector:@selector(Update) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:loop forMode:NSRunLoopCommonModes];