How do I get a view in Interface Builder to load a custom view in another nib?

Question

I am making a custom widget that I would like to use in multiple nibs. So I make a new view nib Screen3, add some buttons, and now want my UIAwesomeSauce widget.

If I just add a view and then change the Class Identity, it doesn't get the subelements from the UIAwesomeSauce nib. Same thing if I go to the Library and switch to Classes. It seems only a UIViewController has the field for "Load from nib", which would be beautiful.

I know I can load the UIAwesomeSauce nib from code, get the top level objects, and place it by hand. But the point of IB is so you don't have to place things in code. Even better would be if I could get UIAwesomeSauce to show up in the Library list itself.

SOLVED - by Nimrod

I can't vote up an answer, even my own? Lame. And hitting enter for a paragraph in a comment submits? Focus fail. And I can't put this in as a comment on the correct answer? Hella lame.

Anyway, dood, that is great. I can make my own widget classes now for goofy Awesome stuff. Make the FileOwner of your UI nib your class, and in it just have a normal UIView with all your stuff. (The single view in the widget's nib can't be the class itself, or you get recursive in initWithCoder.) Then in the nib you want to use it, make a vanilla UIView and change its class. You won't be able to actually see the widget inside that square, but deal.

Self is now a blank view, and tMyActualSelf is the single view that you did the work in in the other nib. Yay!

- (id)initWithCoder:(NSCoder*)coder 
{
    if ((self = [super initWithCoder:coder])) 
    {
        UIView *tMyActualSelf = nil;
        // Initialization code
        NSArray *tNibItems = [[NSBundle mainBundle] loadNibNamed:@"UIAwesomeSauce" owner:self options:nil];
        for (id object in tNibItems) 
        {
            if ([object isKindOfClass:[UIView class]])
                tMyActualSelf = (UIView *)[object retain];
        }   
        if( tMyActualSelf ) 
        {
            tMyActualSelf.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
            [self addSubview:tMyActualSelf];
        }
    }
    return self;
}

Answer 1

I feel your pain when it comes to the UIViewController being the only thing you can specify a nib load with, but I think it's because there has to be a File's Owner that's a controller, or something like that, though I'm not sure why a UIView can't be a File's Owner.

I think you can put things in the library under Custom Objects but I think you'd be limited to putting a UIView in there with the class just set to a custom subclass of UIView. I actually looked into trying to extend interface builder and it looks like you can do it for OS X stuff, but not for iPhone stuff. It involves compiling code for the new widget in interface builder to tell it how to draw the widget just within IB. I think there's actually an OS X template for this.

I think what I'd probably do is create a main view in a nib file that contains all the subviews, then in initWithCoder: in the UIAwesomeSauce thing open the nib file, load the main view, and just place it inside self so that you have an "unnecessary" view between the UIAwesomeSauce view and the subviews (or sub subviews as the case would be.) I'm not sure how inefficient that is, but in messing with some stuff it looks like some views like UIWebView seem to have one of these seemingly unnecssary intermediate views (IIRC).

If you come up with a better solution please tell me because I'd like to know too.

EDIT

Now that I look at it, I think the UIView CAN be the file's owner, you just can't set it up in IB. Basically you'd call the nib load something like this in the UIView subclass:

[bundle loadNibNamed:@"UISpecialSauce" owner:self options:...]

I think if you create outlets in UISpecialSauce or whatever then they should be assigned correctly because of the owner:self.