from http://blog.couchbase.com/photodrop

startListener.swift

    // MARK: - Listener
    func startListener() -> Bool {
        if listener != nil {
            return true
        }
 
        var error: NSError?
        listener = CBLListener(manager: CBLManager.sharedInstance(), port: 0)
 
        // Enable Basic Authentication
        listener.requiresAuth = true
        let username = secureGenerateKey(NSCharacterSet.URLUserAllowedCharacterSet())
        let password = secureGenerateKey(NSCharacterSet.URLPasswordAllowedCharacterSet())
        listener.setPasswords([username : password])
 
        var success = listener.start(&error)
        if success {
            // Set a sync url with the generated username and password:
            if let url = NSURL(string: database.name, relativeToURL: listener.URL) {
                if let urlComp = NSURLComponents(string: url.absoluteString!) {
                    urlComp.user = username
                    urlComp.password = password
                    syncUrl = urlComp.URL
                }
            }

            return true
        } else {
            listener = nil
            return false
        }
    }