Cocoa – Loading NIB file using NSWindowController doesn’t set window or top level objects

You're trying to create the instance of NSWindowController by instantiating it in another nib. However, when you instantiate an object in a nib file, it is initialized by calling -initWithCoder:.

-initWithCoder: is not a designated initializer of NSWindowController, so your instance of NSWindowController never actually loads its nib.

Instead of instantiating your NSWindowController instance by placing it in the MainMenu.xib file in Interface Builder, create it programmatically:

In AppDelegate.h:

@class YourWindowController;
@interface AppDelegate : NSObject
{
    YourWindowController* winController;
}
@end

In AppDelegate.m:

@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification*)notification
{
    winController = [[YourWindowController alloc] init];
    [winController showWindow:self];
}
- (void)dealloc
{
    [winController release];
    [super dealloc];
}
@end

In YourWindowController.m:

@implementation YourWindowController
- (id)init
{
    self=[super initWithWindowNibName:@"YourWindowNibName"];
    if(self)
    {
        //perform any initializations
    }
    return self;
}
@end

Here's what worked for me:

• Open the XIB file causing problems
• Click on file's owner icon on the left bar (top one, looks like a yellow outlined box)
• If you don't see the right-hand sidebar, click on the third icon above "view" in your toolbar. This will show the right-hand sidebar
• In the right-hand sidebar, click on the fourth tab--the one that looks a bit like a newspaper
• Under "Custom Class" at the top, make sure Class is the name of the ViewController that should correspond to this view. If not, enter it
• In the right-hand sidebar, click on the last tab--the one that looks like a circle with an arrow in it
• You should see "outlets" with "view" under it. Drag the circle next to it over to the "view" icon on the left bar (bottom one, looks like a white square with a thick gray outline
• Save the xib and re-run