SFSafariViewController is an implementation of the browser-view
pattern, providing a secure browser tab displayed in the context of the app.
SFSafariViewController was added in iOS 9
SFSafariViewController class has all the properties of the system browser, and is an 'external User-Agent', even though it is presented within the host app.
Regardless of whether the user completes the request in the system browser (as is their choice), or the SFSafariViewController, the return of the token via Custom URI scheme or App-claimed HTTPS URI Redirection the link is the same.
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