Loading Mashups in mobile Applications with Authorization

Hello everyone,

I am developing a native-react app that should open some Mashups in a Webview. Since Webviews in such frameworks do not allow Popups (for the login necessary), I am looking for a way to open the Mashup in the Webview with Authorization. 

The login Credentials are requested from the user beforehand. I already tried to simply open the link of the mashup in the webview and pass the credentials "userid" and "password" in the http header, but I still get the error "401 - not authorized".

Has anyone made experiences with opening mashups in webviews and a working authorization process?

Any hints would be appreciated very much!

Best Regards,

Dominik