Objective-C nil Outlets

Question

I have a class used for a user interface, with two constructors:

- (id)initWithBanner:(NSMutableArray *)banner {  
    if ( ( self = [super initWithNibName:@"UIBanner" bundle:nil] ) ) {
      // ... code...
    }
    return self;
}

- (id)initWithPreview:(NSMutableArray *)previews {
    if ( ( self = [super initWithNibName:@"UIBanner" bundle:nil] ) ) {
      // ... code...
    }
    return self;
}

Inside this two constructors, I use two outlets, a UIPageControl and a UIScrollView, linked with the new XCode 4. Now, if I use the first constructor, initWithBanner, everything works fine (putting a NSLog(@"%@",bannerScroll) gives the relative outlet description) but when I use initWithPreview, my Outlets are nil. What's wrong with that?

Answer 1

Your outlets will not be set until the nib is actually loaded, which occurs when your UIViewController's view property is read. You implement the -viewDidLoad method to handle when your nib has loaded. Also note that the view and nib can be unloaded and loaded multiple times during the life of your UIViewContoller instance.