Where is the window outlet in an NSDocument

问题

My app was converted from a non-document-based app to a document-based one. I did that by creating a subclass of NSDocument, called Document. I also created a Document.xib and set its "File's Owner" to Document.

Now in Document.xib, I can see there is a window outlet in its "File's Owner". I don't have a window outlet defined in Document. Where does it come from? I guess it is from the super class NSDocument, but I have no access to that variable in Document. What's up with this weird window outlet?

回答1:

Have a look at the documentation for -[NSDocument setWindow:]

This method is invoked automatically during the loading of any nib for which this document is the file’s owner, if the file’s owner window outlet is connected in the nib. You should not invoke this method directly, and typically you would not override it either.

NSDocument doesn't deal with NSWindows directly, but it keeps a list of NSWindowControllers that you can access via the -[NSDocument windowControllers] method. My guess is that when setWindow: gets called, it wraps the window in a new NSWindowController and adds it to the list.

You should be able to access the window with something like this:

NSWindowController* controller = self.windowControllers.lastObject;
NSWindow* window = controller.window;

I just made a new project to test it, and this works:

- (void)windowControllerDidLoadNib:(NSWindowController *)aController {
    [super windowControllerDidLoadNib:aController];
    NSLog(@"%@", [self.windowControllers.lastObject window]);
}

来源：https://stackoverflow.com/questions/26580908/where-is-the-window-outlet-in-an-nsdocument