SwiftUI Meets ChatGPT

SwiftUI+ChatGPT.swift

import SwiftUI

struct ContentView: View {
    @StateObject var service = ChatGPTService()
    @State var textResponse = ""
    var body: some View {
        VStack {
            Text("Bot says: \(textResponse)")
            Button {
                Task {
                    let response = try await service.processPrompt(prompt: "Pretend to be a choose-your-own adventure book about Jurassic Park please.")
                    textResponse = response ?? ""
                }
            } label: {
                Image(systemName: "globe")
                    .imageScale(.large)
                    .foregroundColor(.accentColor)
                Text("Hello, world!")
            }
            .padding()
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

class ChatGPTService: ObservableObject {
    let apiKey: String = "this is your api key"
    
    let openAIURL = URL(string: "https://api.openai.com/v1/chat/completions")
    
    public func processPrompt(
        prompt: String
    ) async throws -> Optional<String> {
        
        var request = URLRequest(url: self.openAIURL!)
        request.httpMethod = "POST"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("Bearer \(self.phoneNumber)", forHTTPHeaderField: "Authorization")
        let httpBody: [String: Any] = [
            "model": "gpt-3.5-turbo",
            "messages" : [["role" : "user", "content": prompt]],
        ]
        
        let httpBodyJson = try JSONSerialization.data(withJSONObject: httpBody, options: .prettyPrinted)
        request.httpBody = httpBodyJson
        
        let (data, _) = try await URLSession.shared.data(for: request)
        
        let object = try? JSONSerialization.jsonObject(with: data)

        let responseHandler = OpenAIResponseHandler()
        let openAIResponse = responseHandler.decodeJson(data)
        
        return openAIResponse?.choices.first?.message.content
    }
    
    struct OpenAIResponseHandler {
        func decodeJson(_ data: Data) -> OpenAIResponse? {
            let decoder = JSONDecoder()
            do {
                let product = try decoder.decode(OpenAIResponse.self, from: data)
                return product
                
            } catch {
                print("Error decoding OpenAI API Response")
            }
            
            return nil
        }
    }

    struct OpenAIResponse: Codable {
        var id: String
        var choices: [Choice]
    }

    struct Choice: Codable {
        var index: Int
        var finish_reason: String?
        var message: Message
    }

    struct Message: Codable {
        var role: String
        var content: String
    }
}