Brief demo showcasing ASWebAuthenticationSession

ASWebAuthenticationSessionDemo.swift

import AuthenticationServices

var webAuthSession: ASWebAuthenticationSession?

@available(iOS 12.0, *)
func logInWithBlizzard() {
    //Blizzard OAuth URL
    let authURL = URL(string: "https://myRegioncode.battle.net/oauth/authorize?access_type=online&client_id=myClientID&redirect_uri=myRedirectURI&response_type=code&state=")
    let loginUrlScheme = "myAppName"

    //Initialize auth session
    self.webAuthSession = ASWebAuthenticationSession.init(url: authURL!, callbackURLScheme: loginUrlScheme) { 
        (callBack, error) in

        // handle errors if they occur
        if let authError = error {
            return
        }
        guard let successRedirectURL = callBack else {
            return
        }

        // Get your code from the redirect url. You can also check for the state if needed.
        let authCode = successRedirectURL.lastPathComponent

        // Exchange your authorization code for an access token, and use your token to make calls to the API.
        myRequestTokenFunc(withAuthCode: authCode)
    })

    // Start the session
    self.webAuthSession?.start()
}