title: How do I make a UIAlertView appear only once, at the first start-up of an iPhone app?
body: <p>I'm using the <code>UIAlertView</code> to make a pop-up happen once the app has started up. It works fine but I only want the pop up to appear on the first start-up of the app. At the moment I've got the <code>UIAlertView</code> in the <code>AppDelegate</code> class, in <code>applicationDidFinishLaunching</code> method. Here is my code:</p>
  
  <pre><code>- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
  sleep(4);
  UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Welcome!" message:@"SAMPLE!!!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
  [alert show];
  [alert release];
  </code></pre>
  
  <p>I'm new to app development so sorry if this is simple.</p>