Thanks to http://ijure.org/wp/archives/179 for this code that registers the Settings bundle defaults with the NSUserDefaults class.

NSUserDefaults+registerDefaultsFromSettingsBundle.m

- (void)registerDefaultsFromSettingsBundle
{
NSLog(@"Registering default values from Settings.bundle");
NSUserDefaults * defs = [NSUserDefaults standardUserDefaults];
[defs synchronize];
 
NSString *settingsBundle = [[NSBundle mainBundle] pathForResource:@"Settings" ofType:@"bundle"];
 
if(!settingsBundle)
{
   NSLog(@"Could not find Settings.bundle");
   return;
}
 
NSDictionary *settings = [NSDictionary dictionaryWithContentsOfFile:[settingsBundle stringByAppendingPathComponent:@"Root.plist"]];
NSArray *preferences = [settings objectForKey:@"PreferenceSpecifiers"];
NSMutableDictionary *defaultsToRegister = [[NSMutableDictionary alloc] initWithCapacity:[preferences count]];
 
for (NSDictionary *prefSpecification in preferences)
{
   NSString *key = [prefSpecification objectForKey:@"Key"];
   if (key)
   {
      // check if value readable in userDefaults
      id currentObject = [defs objectForKey:key];
      if (currentObject == nil)
      {
         // not readable: set value from Settings.bundle
         id objectToSet = [prefSpecification objectForKey:@"DefaultValue"];
         [defaultsToRegister setObject:objectToSet forKey:key];
         NSLog(@"Setting object %@ for key %@", objectToSet, key);
         }
      else
         {
         // already readable: don't touch
         NSLog(@"Key %@ is readable (value: %@), nothing written to defaults.", key, currentObject);
         }
      }
   }
 
[defs registerDefaults:defaultsToRegister];
[defaultsToRegister release];
[defs synchronize];
}