How do I add Spotify's URL scheme in Xcode?

I am using Spotify iOS SDK, I've followed the tutorial on the official page and everything was fine, until I tried to submit to iTunes connect for testing and I got an error, saying invalid URL Scheme. This what i intially had in the pllist:

spotify-action://

which I then changed to

spotify-action

This allows me to submit to itunes connect, but the sign in flow is broken - when I click sign in, nothing happens. no errors, no warnings.

If I add the "://" into the URL Scheme, Spotify App would launch and it authenticates correctly

this is the function i am using to login:

func openLoginPage() {
    let auth = SPTAuth.defaultInstance()
    if SPTAuth.supportsApplicationAuthentication() {
        guard let url = auth?.spotifyAppAuthenticationURL() else { return }
        if #available(iOS 10.0, *) {
            if(!UIApplication.shared.openURL(auth!.spotifyAppAuthenticationURL())){
                self.showAlertL(message: "Link won't work for some reason", link: url)
            }
            else{
                print("This works - start screen");
                print(schemeAvailable(scheme: "\(url)"))
            }
            print("This is the URL For Spotify ios 10 \(String(describing: auth?.spotifyAppAuthenticationURL()))")
        } else {
            print("This is the URL For Spotify old \(auth!.spotifyAppAuthenticationURL())")               
            UIApplication.shared.openURL(auth!.spotifyAppAuthenticationURL())
        }
    } else {
        self.authViewController = self.getAuthViewController(withURL: SPTAuth.defaultInstance().spotifyWebAuthenticationURL())
        self.definesPresentationContext = true
        self.present(self.authViewController!, animated: true, completion: { () in })
    }
}

canOpenURL always returns true, regardless if I am using "spotify-action://" or just "spotify-action" in the URL scheme.

UIApplication.shared.canOpenURL(url)

just in case you were wondering, this is the content of the URL (I've removed the redirect URI part)

spotify-action://authorize?
nolinks=true&
nosignup=true&
response_type=code&
scope=streaming%20playlist-read-private%20playlist-modify-public%20playlist-modify-private%20user-read-private&
utm_source=spotify-sdk&
utm_medium=ios-sdk&
utm_campaign=ios-sdk&