How to determine that user runs the app for the first time?

Question

I got a problem of my iOS app recently. In my app, an instruction view will appear at the first time of running, then hide from then on. How can I implement this effect?

Answer 1

Try to use this function:

- (BOOL) isFirstRun
{
  NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];  
  if ([defaults objectForKey:@"isFirstRun"])
  {
    return NO;
  }

  [defaults setObject:[NSDate date] forKey:@"isFirstRun"];
  [[NSUserDefaults standardUserDefaults] synchronize];  

  return YES;
}