title: SwiftUI ShareLink set file name
body: <p>I'm using the <code>ShareLink</code> to share an <code>FileDocument</code> which contains a String. The <code>FileDocument</code> is conform to the <code>Transferable</code> protocol.</p>
  <p>This is the FileDocument Struct:</p>
  <pre><code>struct TransferableDocument: FileDocument, Transferable {
  
    static var transferRepresentation: some TransferRepresentation
    {
        DataRepresentation(exportedContentType: .text) { log in
            log.convertToData()
        }
    }
  
    // tell the system to support only text
    static var readableContentTypes: [UTType] = [.text]
  
    // by default the document is empty
    var text = &quot;&quot;
  
    // this initializer creates a empty document
    init(initialText: String = &quot;&quot;) {
        text = initialText
    }
  
    // this initializer loads data that has been saved previously
    init(configuration: ReadConfiguration) throws {
        if let data = configuration.file.regularFileContents {
            text = String(decoding: data, as: UTF8.self)
        }
    }
  
    // this will be called when the system wants to write the data to disk
    func fileWrapper(configuration: WriteConfiguration) throws -&gt; FileWrapper {
        let data = Data(text.utf8)
        return FileWrapper(regularFileWithContents: data)
    }
  
    func convertToData() -&gt; Data
    {
        return text.data(using: .ascii) ?? Data()
    }
  }
  </code></pre>
  <p>And this is the ShareLink:</p>
  <pre><code>var doc: TransferableDocument
  {
      return TransferableDocument(initialText: &quot;I'm a String&quot;)
  }
  
  ShareLink(item: doc ,preview: SharePreview(&quot;logfile&quot;)) 
  {
      Text(&quot;Share&quot;)
  }
  </code></pre>
  <p>When using AirDrop, the filename is set to the SharePreview title, in this case &quot;logfile&quot;. When sharing it to Apps like Mail, the filename is simply set to &quot;text&quot;.</p>
  <p>Is there any way to set a default filename?</p>