FirebaseSnippets.swift

    @IBAction func didTapEmailButton(_ sender: Any) {
        let authUI = FUIAuth.defaultAuthUI()!
        authUI.delegate = self
        let settings = ActionCodeSettings()
        settings.url = Constants.URLs.login
        settings.handleCodeInApp = true
        settings.setIOSBundleID(Constants.AppInfo.bundleIdentifier)
        authUI.providers = [
            FUIEmailAuth(
                authAuthUI: authUI,
                signInMethod: EmailLinkAuthSignInMethod,
                forceSameDevice: true,
                allowNewEmailAccounts: true,
                actionCodeSetting: settings
            )
        ]
        let provider = authUI.providers.first as! FUIEmailAuth
        provider.signIn(withPresenting: self, email: nil)
    }

    /// For more information, see [FirebaseUI for iOS — Auth](https://github.com/firebase/FirebaseUI-iOS/blob/master/Auth/README.md)
    static func handle(universalLink link: URL) -> Bool {
        guard
            let emailLinkString = link.queries["link"] as? String,
            let emailLink = URL(string: emailLinkString)
            else { return false }
        return FUIAuth.defaultAuthUI()?.handleOpen(emailLink, sourceApplication: nil) ?? false
    }