How do I programmatically change a custom view object's member variables?

I appreciate you taking the time to read this and hopefully help me out!

I am writing my first program in Xcode 4, using Objective-C and Cocoa for the first time. I have been following the tutorials, but at this point I want to display custom graphics using a custom view, where the graphics change based on the values in my model object.

My controller class, GameController, based on NSObject, creates my model object during initialization, and successfully receives button action messages, updates the model object appropriately, and updates text strings on the window in return using its outlets. I accomplished this by creating an NSObject object in my xib file (which is called the default (?) name of MainMenu.xib, but it includes all the UI in my application), using the utilities pane to set its class to GameController, and then connecting its actions and outlets to the appropriate UI elements.

I have dragged a custom view into my window, and used the utilities pane to set its class to my custom view class, BoardView, which is based on NSView. In BoardView, I have overridden drawRect: to fill in the background of my view with a blue color, and then draw each of the graphics defined by my model class (GameStatus).

The problem is, I do not know how to access the data in GameStatus from my BoardView class, or have GameController update a member variable of BoardView. I have not instantiated BoardView anywhere besides in Interface Builder, by dropping a custom view on my window. I do not have a BoardView object in my xib file (the column or list on the left side in Interface Builder).

I tried to create an outlet to a BoardView object in my GameController class (which does have an object in my xib, as I mentioned above), and connecting that outlet to the BoardView custom view in my window, and Interface Builder seemed fine with that. However, when I run the program, the value of the BoardView outlet pointer in my GameController class is 0x0. It seems like the outlet is not being connected to a BoardView object. I don't know if I need to do something else in Interface Builder to make an actual object (I tried creating one in the list to the left, but then couldn't figure out a way to connect it to the actual custom view displayed on the window).

To add to the confusion, when I run my application, the BoardView area of the window will display the blue background, and in fact any other graphics which I define in the drawRect: function. However, without 开发者_Python百科any way to talk to my model object, I can't change the graphics based on the state of the model. I'm not sure if the fact that the hard-coded graphics are displaying correctly means that there is an object there somewhere, or whether it is somehow drawing based on the general template of the class somehow. The latter doesn't really make sense to me, but if the former is true, I'm can't figure out how to talk to that object from other parts of my code.

I feel like I'm just missing some basic understanding of how Xcode / Interface Builder creates objects or something. I would really appreciate someone telling me exactly what I'm missing here in the connection between my MVC objects / classes.

Thank you in advance for any help you can give me!

EDIT 2011/09/06: To download a copy of my project to take a look at it, go here: http://talix.homeip.net/2011/rival/ That's my home server and I'm an amateur at this, so please leave a comment if it isn't working. Thanks! Also, if there is a better way to respond to comments other than editing my original post, please let me know; I'm also new to this website. ;-)

-Joe

It sounds like you're only instantiating one GameController and one BoardView, and that's happening in the nib.

This, then, is the heart of the problem:

I tried to create an outlet to a BoardView object in my GameController class (which does have an object in my xib, as I mentioned above), and connecting that outlet to the BoardView custom view in my window, and Interface Builder seemed fine with that. However, when I run the program, the value of the BoardView outlet pointer in my GameController class is 0x0. It seems like the outlet is not being connected to a BoardView object.

Where in your code are you needing a reference to your BoardView but getting nil? Is that in GameController's init method, or in some other method of GameController?

If it's inside init, this is what I'd expect. The code that loads nibs must initialize the objects before it connects the outlets.

(If it's outside of init, I'd suggest starting by disconnecting and reconnecting the outlet.)

• View = BoardView
• Controller = GameController
• Model = GameStatus

In MVC, the controller usually brokers communication between the model and the view, so I suggest you handle it this way:

1. Add a gameController outlet to BoardView and connect it to your game controller.
2. In drawRect, have the BoardView get the game status from the game controller.

I also suggest you make GameController your application's delegate:

1. Delete RivalAppDelegate.[hm].
2. In your nib, delete the reference to Rival App Delegate, and connect the Game Controller reference to the File's Owner delegate outlet.
3. You've got two instance of BoardView in your nib. Hook up the one inside your window to the boardView outlet of GameController and delete the other.
4. In GameController.h, after @interface GameController : NSObject, add <NSApplicationDelegate>
5. In GameController.m, implement applicationDidFinishLoading and set up your application there. (You can even call setGameStatus there if you want to.)