I have a UITabBar Application with two views that load large amounts of data from the web in their "viewWillAppear" methods. I want to show a progress bar or an activity indicator while this data is being retrieved, to make sure the user knows the app isn't frozen.

I am aware that this has been asked before. I simply need some clarification on what seems to be a rather good solution.

I have implimented the code in the example. The question's original asker later solved their problem, by putting the retrieval of data into another "thread". I understand the concept of threads, but I do not know how I would impliment this.

With research, I have found that I need to move all of my heavy data retrieval into a background thread, as all of the UI updating occurs in the main thread.

If one would be so kind as to provide an example for me, I would be very appreciative. I can provide parts of my existing code as necessary.