Cannot Save in a Document-Based Application

Question

I created new Document-Based-App.

I implemented dataOfType in subclass of NSDocument

- (NSData*) dataOfType:(NSString *)typeName error:(NSError *__autoreleasing *)outError
 {
         return [NSKeyedArchiver archivedDataWithRootObject:bcmwc.bindingsController.arrangedObjects];
 }

in xib http://i.minus.com/iH2Rj9v5oOhTn.png

When I click "Save" from menu nothing's gonna happen, any errors in console. I set a breakpoint in dataOfType, and when I clicked "Save", application didn't stop.

Any suggestions?

EDIT

I think it may be connected with fact I use custom NSWindowController, and custom xib. I made a test when I load custom xib, everything is fine dataOfType method is invoked etc..

Should I connect in some way my custom xib (window) with subclass of NSDocument?

"When I click "Save" from menu nothing's gonna happen, any errors in console." please explain this better. — John Riselvato
Also please take care to choose more precise subject names. "First Document-Based Application" tells us exactly nothing about the nature of your question. — Joshua Nozzi

Joshua Nozzi Joshua Nozzi · Accepted Answer · 2011-11-16T19:03:04

It looks like your Save menu item is connected properly, so let's concentrate on the code (+1 for having posted it in the first place).

You do nothing in your code to ensure -archivedDataWithRootObject: returns valid data or set an error if it doesn't. My best guess (because you haven't provided nearly enough detail to do anything but guess) is that you're returning nil because your call to -archivedDataWithRootObject: is doing the same. Check to see if you get valid data and set the outError if not.

Why would you get nil? Perhaps one or more of the objects in the object graph created by archiving your array controller's -arrangedObjects array isn't <NSCoding> compliant. This is likely the case if your array controller holds objects of a custom class you created rather than a standard Property List container.

Read the Archives and Serializations Programming Guide (in particular, the Encoding and Decoding Objects section) to learn how to make your custom class <NSCoding> compliant so that it knows how to serialize itself (write itself into a byte stream suitable for NSKeyedArchiver, etc. and create an instance of itself from such a byte stream).

Also, you really need to learn to use the debugger. You're groping around in a dark cave with lots of pitfalls and no flashlight without it. Try setting a breakpoint in methods you expect to be called. If they're not called, you can check outlets/actions, etc. If they are, you can step through each line and make sure everything is executing as you expected. If you write a little more verbose code, you can more easily inspect the results when paused in the debugger. Two lines in your case will help you more than one:

- (NSData*) dataOfType:(NSString *)typeName error:(NSError *__autoreleasing *)outError
{
    NSData * myData = [NSKeyedArchiver archivedDataWithRootObject:bcmwc.bindingsController.arrangedObjects];
    // You should be handling nil (setting a descriptive error) here if (!myData)...
    return data; // breakpoint here; you should now see myData is likely nil
}

Cannot Save in a Document-Based Application

1 Answers