Swifter (Twitter SDK) and SwiftUI: problems with swifter.authorize – code in succes: Swifter.TokenSuccessHandler never gets accessed

I am calling

Code Block 
Swifter.authorize(withCallback: URL, presentingFrom: UIViewController, success: Swifter.TokenSuccessHandler, failure: Swifter.TokenFailureHandler)

from a buttonpress in a

Code Block 
UIViewControllerRepresentable

. When clicking the Button, I am directed to a website in Safari to authorize my App. So far so good. After authorizing my app and getting returned by the Callback URL: “MyTwitterApp://“ neither the code inside

Code Block 
Swifter.TokenSuccessHandler

nor inside

Code Block 
Swifter.TokenFailureHandler

is run. Even the debugger does not step into it. In addition, at buildtime I get many warnings about

Code Block 
init(account:)

being deprecated since iOS 11.0 along other stuff. As I am using the newest version of Swifter and as I have found a fairly recent tutorial (definitely created after the launch of iOS 11) showing Swifter working, I am not sure if that creates any problem.

However, my main complaint is, that I am not able to authorize my app, as the code in success is not accessed.