pod KakaoSDKUser

import UIKit
import KakaoSDKAuth

class AppDelegate: UIResponder, UIApplicationDelegate {
 
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
     
     //카카오톡 SDK 초기화하기
        KakaoSDK.initSDK(appKey: Appkey.kakao)
     }

    func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
        //카카오톡
        if AuthApi.isKakaoTalkLoginUrl(url) {
            return AuthController.handleOpenUrl(url: url)
        }
        
        return false
    }

import UIKit
import KakaoSDKAuth
 
 class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
        if let url = URLContexts.first?.url {
            if AuthApi.isKakaoTalkLoginUrl(url) {
                _ = AuthController.handleOpenUrl(url: url)
            }
        }
    }
 }

         if UserApi.isKakaoTalkLoginAvailable() {
             UserApi.shared.loginWithKakaoTalk(channelPublicIds: nil, serviceTerms: nil) { (oauthToken, error) in
                 if let error = error {
                 }
                 else {
                 //(1) 카카오 앱으로 로그인 성공
                 
                 }
             }
         }
         else {
            //(2) 카카오 계정으로 로그인
            UserApi.shared.loginWithKakaoAccount(prompts: nil, channelPublicIds: nil, serviceTerms: nil) { (oauthToken, error) in
             if let error = error {
                 print(error)
             }
             else {
                 print("Login Kakao account Success.")
                 //카카오 계정으로 로그인 성공
             }
         }
         }