Beta 2 of SwiftUI DocumentGroup does not support complex file formats

I was wrong. It appears that it does, you just need to do it right.

Document.init() is called on when the + is tapped. This allows you to set up the generic data structure. Then write() is called and you can alter the fileWrapper() to be a directory() and then add a child fileWrapper() for files within the directory.

Then, to launch the DocumentEditor, a call is made to Document.ini(fileWrapper: FileWrapper, contentType: UTType) and this is passed to the DocumentEditor. 

Once the Document is created correctly, the system works. Hope this helps someone else struggling with this sequence.

@cwooloszynski This is very interesting, can you post some sample code? Really appreciate it.

@cwoloszynski, I'm having the exact issue you discussed and I can't quite understand how you fixed it. For the exported/imported type identifier "conforms to" did you finally use "com.apple.package"?

I want a directory structure that looks like:

     <UserChosenName.pspkg>/.    // directory package containing my document data and images
           PhraseSet.dat   // regular file with serialized data from snapshot
           Images/              // subdirectory for images (populated directly from my app as needed)
                 Image0.png
                 Image1.png
                 ....

I'm using the following class for the FileWrapper to encapsulate what I think I need to do. Can you see something I'm doing incorrectly?

    var snapshot: Data

    init(withSnapshot: Data) {
        self.snapshot = withSnapshot
        let sWrapper = FileWrapper(regularFileWithContents: snapshot)
        let dWrapper = FileWrapper(directoryWithFileWrappers: [:])
        super.init(directoryWithFileWrappers: ["PhraseSet.dat" : sWrapper,
                                               "Images" : dWrapper ])

        // TO BE DONE: create subdirectory for images. Writing of
        // images is done outside of the ReferenceFileDocument
        // functionality.
    }

    override func write(to url: URL,
                        options: FileWrapper.WritingOptions = [],
                        originalContentsURL: URL?) throws  {
        if let fileWrappers = fileWrappers {
            for (_, wrapper) in fileWrappers {
                try wrapper.write(to: url, options: options,
                                  originalContentsURL: originalContentsURL)
            }
        }
    }

    required init?(coder inCoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}