Dropbox can not authenticate using Xamarin.Forms - xamarin

Question

I am trying to authenticate in Dropbox using Xamarin.Forms, I use the following code.
this.oauth2State = Guid.NewGuid().ToString("N");
var authorizeUri = DropboxOAuth2Helper.GetAuthorizeUri(OAuthResponseType.Token, AppKeyDropboxtoken, new Uri(RedirectUri), this.oauth2State, false, false, null, loginAgain);
webView = new CustomWebview
{
Source = authorizeUri.AbsoluteUri
};
webView.Navigating += this.WebViewOnNavigating;
//Grid Layout
Grid lyStack = new Grid
{
Children =
{
webView,
lyTitle,
},
HorizontalOptions = LayoutOptions.FillAndExpand,
VerticalOptions = LayoutOptions.FillAndExpand,
Padding = new Thickness(0, 20, 0, 0),
};
this.Content = lyStack;
But when I submit the App to production, I get the following error message:
Hi there,
Your production key request was declined for the following reason:
Your apps currently process the OAuth app authorization flow inside a
web view, instead of the system browser. The OAuth app authorization
flow should be processed in the user's system browser. See here for
more information:
https://www.dropbox.com/developers/documentation/http/documentation#oauth2-authorize
.
If you believe your app shouldn't have been declined, or to resubmit
your request, please email us at api-program#dropbox.com.

Answer 1

Using Xamarin.Auth solved the problem, that is the way it worked:
private string oauth2State;
private const string RedirectUri = "https://www.myredirecturl.com/en/";
private string AccessToken { get; set; }
private const string AppKeyDropboxtoken = "xxxxxxxxxxxxxxx";
private void openDropbox()
{
this.oauth2State = Guid.NewGuid().ToString("N");
var authorizeUri = DropboxOAuth2Helper.GetAuthorizeUri(OAuthResponseType.Token, AppKeyDropboxtoken, new Uri(RedirectUri), this.oauth2State, false, false, null, false);
//Authorize URI
OAuth2Authenticator auth = new OAuth2Authenticator
(
clientId: AppKeyDropboxtoken,
scope: "",
authorizeUrl: new Uri(authorizeUri.AbsoluteUri),
redirectUrl: new Uri(RedirectUri),
isUsingNativeUI: false
);
auth.Completed += (sender, eventArgs) =>
{
if (eventArgs.IsAuthenticated)
{
Debug.Write("IsAuthenticated . . . . . ");
// Use eventArgs.Account to do wonderful things
this.AccessToken = eventArgs.Account.Properties["access_token"].ToString();
Debug.WriteLine("AccessToken: " + this.AccessToken);
//Do Something
}
};
var presenter = new Xamarin.Auth.Presenters.OAuthLoginPresenter();
presenter.Login(auth);
}
And intialize on the plataforms the Presenter,
Android on your OnCreate method
global::Xamarin.Auth.Presenters.XamarinAndroid.AuthenticationConfiguration.Init(this, bundle);
iOs on your AppDelegate.cs
global::Xamarin.Auth.Presenters.XamarinIOS.AuthenticationConfiguration.Init();