Introduction

I haven’t had the opportunity to build a chatbot before. This topic was trending some time ago, and I always wanted to implement it myself. In this article, I will focus on the steps you need to know to successfully build and run a chatbot application.

First Step

The first step is to add the OpenAI dependency to your project:

.package(url: "https://github.com/MacPaw/OpenAI.git", branch: "main")

dependencies: [
    .byNameItem(
        name: "OpenAI",
        condition: .when(platforms: [
            .iOS,
        ])
    ),
],

Second Step

The second step is to generate an OpenAI key and replace it inside your project.

Third Step

The third step is to create ChatGPTService and add the getAssistantResponse method that will be receiving responses from the GPT model:

import Foundation
import OpenAI

final class ChatGPTService {
    private let client: OpenAI

    init() {
        client = OpenAI(apiToken: "YOUR_TOKEN")
    }

    func getAssistantResponse(_ messages: [Message], _ completion: @escaping (Message?) -> Void) {
        let query = ChatQuery(
            messages: messages.map {
                .init(role: .user, content: $0.content)!
            },
            model: .gpt3_5Turbo
        )

        client.chats(query: query) { result in
            switch result {
            case let .success(success):
                guard let choice = success.choices.first,
                      let message = choice.message.content?.string
                else { completion(nil); return }
                DispatchQueue.main.async {
                    completion(Message(content: message, isUser: false))
                }
            case let .failure(error):
                print(error)
                completion(nil)
            }
        }
    }
}

Fourth Step

The fourth step is to add ChatService that will be responsible for adding, sending messages, and redrawing the UI:

import Foundation

struct Message: Identifiable {
    var id: UUID = .init()
    var content: String
    var isUser: Bool
}

final class ChatService: ObservableObject {
    @Published private(set) var messages: [Message] = []
    private let chatGPTService: ChatGPTService = .init()

    func sendMessage(_ message: Message) {
        messages.append(message)
        chatGPTService.getAssistantResponse(messages) { [unowned self] message in
            if let message = message {
                messages.append(message)
            }
        }
    }
}

Fifth Step

The fifth step is to connect the UI and ChatService:

import SwiftUI

struct ChatView: View {
    @StateObject private var chatService: ChatService = .init()
    @State private var message: String = ""

    var body: some View {
        VStack {
            ScrollView {
                ForEach(chatService.messages) { message in
                    Text(message.content)
                }
            }
            HStack {
                TextField("Message", text: $message)
                Button("Send") {
                    chatService.sendMessage(Message(content: message, isUser: true))
                }
            }
        }
    }
}

Caveats

Be aware of API quota limits; you can exceed your limits very quickly.

Resources

https://www.youtube.com/watch?v=fkg3UzopiHY&ab_channel=JaredDavidson

Thank you for reading! 😊