SDK1.3.13 and Swift

hello,
thanks for your reply, I make some progress because i discovered an example (https://github.com/tkunstek/elevenchat/tree/master/ElevenChat)

Now i am facing an issue when I try to loadmetadata
loadedMetadata failed with error: Error Domain=dropbox.com Code=400 "The operation couldn’t be completed. (dropbox.com error 400.)" UserInfo=0x7fe6f1411c10 {path=/, error=App folder (sandbox) access attempt failed because this app is not configured to have an app folder. Should your access type be 'dropbox' instead?}

my code below:

// dropbox rest client
private var dbRestClient: DBRestClient?

@IBAction func btconnect(sender: AnyObject) {
    if !DBSession.sharedSession().isLinked() {
        // should let use know why ayou are asking for dropbox permissions
        // now ask for permission
        DBSession.sharedSession().linkFromController(self)
    }
    if dbRestClient == nil {
        dbRestClient = DBRestClient(session: DBSession.sharedSession())
        dbRestClient!.delegate = self
    }
}

@IBAction func btList(sender: AnyObject) {
    dbRestClient?.loadMetadata("/")
}

func restClient(client: DBRestClient!, loadedMetadata metadata: DBMetadata!){
    if (metadata.isDirectory) {
        println("Folder \(metadata.path) contains:")

        for FILE in metadata.contents {
            println(" \(FILE.filename)");
        }
    }
}

func restClient(client: DBRestClient!, loadMetadataFailedWithError error: NSError!){
    println("loadedMetadata failed with error: \(error)")
}

any idea ?
Thanks
Sébastien