title: Have data retrieved by separate thread returned to main thread for display in UI
body: <p>I have an application that has a button and a label.  When the button is clicked, an asynchronous separate thread is started that calls a Web Service.  Once the Service responds, the thread then passes the data back to a function in the MainViewController in the form of an object.  However since that function is getting called by the separate thread, it has no way of displaying that data in the UI (main thread).  When I try to assign text to a label or change a picture or do any UI manipulation at all, nothing happens.. All UI objects are NULL objects when the function runs.  Does anyone have a suggestion as to how I might be able to get data back into the main thread from the spawned thread?  </p>
  
  <p>Thought - </p>
  
  <p>I suppose I could store the object in a global variable, but still need to be able to notify the main thread that there is data to go get and display.  </p>