NSTimer inside global queue is not called when the

Question

I want to run a selector using NSTimer which contains some network calls and some other tasks. I want to do that on global queue.

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSTimer * myTimer=[[NSTimer alloc]init];
        myTimer = [NSTimer timerWithTimeInterval:10*60 target:self selector:@selector(syncGroupAutomatically) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:myTimer forMode:NSRunLoopCommonModes];
        [[NSRunLoop currentRunLoop] run];
    });

-(void)syncGroupAutomatically
{
    NSLog(@"Some Network calls and some other things\n");
}

If I run this code, it works fine when app is in foreground, but as soon as I press the home button it stops calling the syncGroupAutomatically method.

If anybody having any idea how to run this NSTimer even when app is in the background. Please help me.