AppDelegate.swift

import UIKit
import StreamChatClient

...
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        /// 1: Create a `ChatClientConfig` with the API key.
        let config = ChatClientConfig(apiKeyString: "kvgjrn7nmuuj")

        /// 2: Set the shared `ChatClient` instance with the config and a temporary token provider.
        ChatClient.shared = ChatClient(config: config, tokenProvider: .anonymous)
        return true
    }
...