Calling a method only on the initial launch of an application

Question

How do you call a method on only the initial launch of an application? For example, if you wanted to put a tutorial UIAlertView on the very first launch but never again after that?

Answer 1

Use the NSUserDefaults for this. Store a BOOL there saying if its firstlaunch, and set it in applicationDidFinishLaunching. Then then only time that is false is after fresh installs of the app.

Answer 2

Easy. When your app launches, check [NSUserDefaults standardUserDefaults] for the presence of a bool that you put in there. If the boolean isn't there (or it's not YES), then show the alert and save the boolean back into NSUserDefaults as YES.

It's all of about 4 lines of code:

if ([[NSUserDefaults standardUserDefaults] boolForKey:@"HasShownInitialAlert"] == NO) {
  UIAlertView * alert = [[UIAlertView alloc] init...];
  [alert show];
  [alert release];
  [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"HasShownInitialAlert"];
}