AppleLogin#4.swift

extension LoginViewController: ASAuthorizationControllerDelegate, 
	ASAuthorizationControllerPresentationContextProviding {
    
    func presentationAnchor(for controller: ASAuthorizationController) -> ASPresentationAnchor {
        return self.view.window!
    }   

    func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
        // TODO
    }
    
    func authorizationController(controller: ASAuthorizationController, didCompleteWithError error: Error) {
        // handle error
    }
}