Question

I am going through several example code banks and tutorials and just completely stumbling, a lot of it is due to the fact that these tutorials are written for Xcode < 4.2 and ARC changes a few things.

I am attempting to build an interface with an MVC design pattern. I am using the basic template provided for the Application Delegate. I have added a class called MainWindowController which inherits from NSWindowController. In the Interface Builder, firstly I removed the Window object in the MainMenu nib file (because I want it in a separate file). I create a new Interface called MainWindow(.xib) I change the file owner to MainWindowController I add the Delegate to the Object List. Now at this point something is not clicking.

I do not fully grasp how or what I need to implement in order for the Delegate to essentially load and launch the Window Controller. First I tried linking the outlet for “delegate” in the Window to the actual application delegate (called AppDelegate) and then linking the Window Outlet in the Delegate class to the Window in Interface Builder.

I would like an answer to this but I would be far more happy with the correct documentation describing this process. I’m sure there is something on MacDev but I’m having trouble finding it.

Here’s what I’m working with:

  @class MainWindow;

  @interface AppDelegate : NSObject <NSApplicationDelegate>


  @property (strong) MainWindow *mainWindowController;
  @property (assign) IBOutlet NSWindow *window;

  @property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
  @property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
  @property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;

  - (IBAction)saveAction:(id)sender;

  @end

…

  @implementation AppDelegate

  @synthesize window;
  @synthesize mainWindowController;
  @synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
  @synthesize managedObjectModel = __managedObjectModel;
  @synthesize managedObjectContext = __managedObjectContext;

  - (void)applicationDidFinishLaunching:(NSNotification *)aNotification
  {
      MainWindow *controller = [[MainWindow alloc] initWithWindowNibName:@"MainWindow"];
      mainWindowController = controller;

     // ... the rest handles the ManagedObject Models...

Solution to date:

@synthesize mainWindowController = _mainWindowController; // IBOutlet is linked in IB
//...
- (void) applicationDidFinishLaunching: (NSNotification *) aNotification
{
    //... initialization of event handling etc...
    if ( !_mainWindowController ) _mainWindowController = [[ MainWindowController alloc] initWithWindowNibName:@"MainWindow"];
    [_mainWindowController showWindow: self];
    // ...

The application delegate can manage an NSWindow in the main nib file or it can delegate that task to a controller (NSWindowController) which is typical of document based applications or MVC design patterns. The default nib file specified by the Basic-info.plist defines which nib file is loaded. Typically the default nib should be the main menu, which loads the delegate as well. The delegate should then by means of applicationDidFinishLoading: or awakeFromNib: perform initialization of the controllers and continue appropriate delegation in accordance with the delegation and mvc design patterns.

The main problem I was having was launching the window, which is done by showWindow: . The exacerbation of this problem stemmed from source code from a very old Mac OS X project that used deprecated functions and methods to accomplish delegation and led me down the wrong path. Thanks for the answer, it ultimately had me look in the right place for the right questions and I found the right answer.

Answer 1

Your problem is that in that second xib, “MainWindow”, a new AppDelegate object is being created that has absolutely nothing to do with the AppDelegate object in the “MainMenu” xib. The objects in each xib are real objects that get serialized and then loaded at runtime.

This specific issue will be addressed in the Resource Management Guide, “Nib Loading”. I can also suggest “Core Application Design”.