an example for @r_plus

slaveplay.m

-(void) setMasterToggle:(id)value specifier:(id)specifier {
  // You'd set the "set" property for your switch in your plist to
  // "setMasterToggle:specifier:" so this gets called
  [self setPreferenceValue:value specifier:specifier];

  BOOL boolValue = [value boolValue];

  // "SlaveToggle" is the ID of the toggle that depends on this switch

  PSSpecifier* slaveSpecifier = [self specifierForID:@"SlaveToggle"];
  if (!boolValue)
    [self setPreferenceValue:[NSNumber numberWithBool:NO] specifier:slaveSpecifier];
  [slaveSpecifier setProperty:[NSNumber numberWithBool:boolValue] forKey:@"enabled"];

  // Of course, you might want to split that behavior out into another method
  // you could call during your initializer otherwise it will remain enabled
  // when you first launch the prefs bundle.

  [[NSUserDefaults standardUserDefaults] synchronize];
}