DropboxService.Authorize

DropboxService.cs

  /// <summary>
        ///     <para>Runs the Dropbox OAuth authorization process if not yet authenticated.</para>
        ///     <para>Upon completion <seealso cref="OnAuthenticated"/> is called</para>
        /// </summary>
        /// <returns>An asynchronous task.</returns>
        public async Task Authorize()
        {
            if (string.IsNullOrWhiteSpace(this.AccessToken) == false)
            {
                // Already authorized
                this.OnAuthenticated?.Invoke();
                return;
            }

            if (this.GetAccessTokenFromSettings())
            {
                // Found token and set AccessToken 
                return;
            }

            // Run Dropbox authentication
            this.oauth2State = Guid.NewGuid().ToString("N");
            var authorizeUri = DropboxOAuth2Helper.GetAuthorizeUri(OAuthResponseType.Token, "yourDrobboxAppKey", new Uri("YourDropboxRedirectUri"), this.oauth2State);
            var webView = new WebView { Source = new UrlWebViewSource { Url = authorizeUri.AbsoluteUri } };
            webView.Navigating += this.WebViewOnNavigating;
            var contentPage = new ContentPage { Content = webView };
            await Application.Current.MainPage.Navigation.PushModalAsync(contentPage);
        }