title: Meaning of symbol ^ in Objective C
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1912023/caret-in-objective-c">Caret in objective C</a><br>
    <a href="https://stackoverflow.com/questions/3499186/what-does-this-syntax-mean-in-objective-c">What does this ^ syntax mean in Objective-C?</a>  </p>
  </blockquote>
  
  
  
  <p>I am tired by searching the meaning of symbol ^ in Objective C. I have seen it in lot of projects especially in back ground running tasks. I will put a link 
  <a href="http://developer.apple.com/library/ios/#samplecode/StitchedStreamPlayer/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010092" rel="noreferrer">http://developer.apple.com/library/ios/#samplecode/StitchedStreamPlayer/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010092</a>
  and in <code>MyStreamingMovieViewController.m</code> you can find the following inside - <code>(IBAction)endScrubbing:(id)sender method</code>.</p>
  
  <pre><code>timeObserver = [[player addPeriodicTimeObserverForInterval:CMTimeMakeWithSeconds(tolerance, NSEC_PER_SEC) queue:dispatch_get_main_queue() usingBlock:
                           ^(CMTime time)
                           {
                               [self syncScrubber];
                           }] retain];
      }
  </code></pre>
  
  <p>Also <a href="http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html" rel="noreferrer">http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html</a>  </p>
  
  <pre><code>- (void)applicationDidEnterBackground:(UIApplication *)application
  {
  UIApplication*    app = [UIApplication sharedApplication];
  
  bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
      // Clean up any unfinished task business by marking where you.
      // stopped or ending the task outright.
      [app endBackgroundTask:bgTask];
      bgTask = UIBackgroundTaskInvalid;
  }];
  
  // Start the long-running task and return immediately.
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
  
      // Do the work associated with the task, preferably in chunks.
  
      [app endBackgroundTask:bgTask];
      bgTask = UIBackgroundTaskInvalid;
  });
  }
  </code></pre>
  
  <p>Please let me know the answer.</p>