Converting a basic Cocoa application to a document-based application

Question

My team and I have been working on an existing, non-document-based Cocoa application. This is our first Cocoa app, although we've done a number of iOS apps thus far.

The app really should be document-based, though, so I've begun trying to convert it. But things here & there don't seem to be working. For example, the File -> Open menu item is permanently disabled (although I finally got the File -> Save menu item to enabled; initially it wouldn't). In addition, I can click the red X to close a window, although the File -> Close menu item itself is disabled; however, when I close the window via the X button, the dealloc method in my NSDocument implementation (SPDocumentInfo) is not invoked. I created a sample, brand-new document-based app just for comparisons; when I close a window there, the SPDocument implementation's dealloc method is indeed invoked (as I'd expect.) So that concerns me.

I made a lot of changed to the project here and there; they include:

Made SPDocumentInfo extend SPDocument like so in the .h file:
```
@interface SPDocumentInfo : NSDocument <NSWindowDelegate>
```

Implemented the following in SPDocumentInfo:

- (NSString *)windowNibName {
    return @"SPDocument";
}

- (void)windowControllerDidLoadNib:(NSWindowController *) aController {
    [super windowControllerDidLoadNib:aController];
}

- (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError {
    NSString *xml = [self toXml];
    return [xml dataUsingEncoding:NSUTF8StringEncoding];
}

- (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError {
    // will make this work later
    if ( outError != NULL ) {
        *outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:unimpErr userInfo:NULL];
    }
    return YES;
}

Edited the .plist file to add "Document types". Among other things, defined "Cocoa NSDocument Class" = "SPDocumentInfo".
Altered some connections in SPDocumentInfo to match the connections in the sample document-based app. For example, in SPDocument.nib, the File's Owner (which represents SPDocumentInfo) is the Window's delegate.

So, I'm wondering if there are other sorts of things I might be missing in converting to a doc-based app. Or, are there any guides on how to do this? (I've looked but couldn't find any). Or should I just start over with a new document-based app and try to retrofit all of our stuff into it? In general, does anyone have any experience with this?

Quick update, in case anyone is following. I realized that earlier, we'd mucked around a bit with connecting some menu items to specific outlets we'd created, rather than letting them remain pointed to their default First Responder outlets. Once I restored the default connections, the menu items became enabled. As far as the dealloc method not being called as expected, I suspect that we have an issue of circular dependencies, where classes contains references to each other and therefore never get to a retain count of zero (which, I guess, is a whole other topic). So we might be able to solv — Dave Taubler
Another update: I don't think the issue is one of circular dependencies. I overrode the release methods in both my SPDocumentInfo class, and the MyDocument class in the sample app. When I close a window in the sample app, release is called by [NSDocumentController removeObject] and [NSWindowController _windowDidClose] (as well as a few autorelease pool pops). But none of that happens to SPDocumentInfo when I close the window in my app. So somehow, the document controller and/or window controller is not behaving as expected in my app. — Dave Taubler

Hans Hans · Accepted Answer · 2017-07-12T09:36:42

An often found suggestion is to create a new document based application and move all you existing code in there. This can be cumbersome for a large workspace with all kinds of stuff nicely configured. Let alone breaking version control.

I took the following simple steps and it worked:

Generate a document based application

from this this generated project, copy the following section from the Info.plist (open the file with a normal text-editor):

<key>CFBundleDocumentTypes</key>
<array>
    <dict>
        <key>CFBundleTypeExtensions</key>
        <array>
            <string>mydoc</string>
        </array>
        <key>CFBundleTypeIconFile</key>
        <string></string>
        <key>CFBundleTypeName</key>
        <string>DocumentType</string>
        <key>CFBundleTypeOSTypes</key>
        <array>
            <string>????</string>
        </array>
        <key>CFBundleTypeRole</key>
        <string>Editor</string>
        <key>NSDocumentClass</key>
        <string>$(PRODUCT_MODULE_NAME).Document</string>
    </dict>
</array>

and paste it in the Info.plist file in your own project.

Copy Document.swift from the generated document-based project into your own project.

it contains a method:

override func makeWindowControllers() {
    // Returns the Storyboard that contains your Document window.
    let storyboard = NSStoryboard(name: "Main", bundle: nil)
    let windowController = storyboard.instantiateController(withIdentifier: "Document Window Controller") as! NSWindowController
    self.addWindowController(windowController)
}

It creates a new window just the way you application normally would. If you storyboard has only one windowcontroller the 'withIDentifier'-field can contain something arbitrary. If you have more window controllers in your storyboard, the identifier needs to correspond to the right windowcontroller for new documents.

Converting a basic Cocoa application to a document-based application

4 Answers