NSViewController responder chain integration

respondersview.h

//
//  RespondersView.h
//  RespondersView
//
//  Created by Panupan Sriautharawong on 9/13/11.
//  Copyright 2011 Panupan.com. All rights reserved.
//

#import <Cocoa/Cocoa.h>

// Allows a NSViewController to be automatically added to the responder chain
@interface RespondersView : NSView {
    IBOutlet NSViewController *viewController;
}

@end

respondersview.m

//
//  RespondersView.m
//  RespondersView
//
//  Created by Panupan Sriautharawong on 9/13/11.
//  Copyright 2011 Panupan.com. All rights reserved.
//

#import "RespondersView.h"

@implementation RespondersView

- (void)setViewController:(NSViewController *)newController
{
    if (viewController)
    {
        NSResponder *controllerNextResponder = [viewController nextResponder];
        [super setNextResponder:controllerNextResponder];
        [viewController setNextResponder:nil];
    }
    
    viewController = newController;
    
    if (newController)
    {
        NSResponder *ownNextResponder = [self nextResponder];
        [super setNextResponder: viewController];
        [viewController setNextResponder:ownNextResponder];
    }
}

- (void)setNextResponder:(NSResponder *)newNextResponder
{
    if (viewController)
    {
        [viewController setNextResponder:newNextResponder];
        return;
    }
    
    [super setNextResponder:newNextResponder];
}
@end

*** Assertion failure in -[xxxx setNextResponder:], /Library/Caches/com.apple.xbs/Sources/AppKit/AppKit-1404.46/Controllers/NSViewController.m:513
<xxxx 0x608000140bb0> is making itself its own next responder!