iOSでChatGPTのAPIを使う

import Foundation

struct ChatMessage: Identifiable {
    enum Role: String {
        case user
        case assistant
    }
    
    let id = UUID()
    let role: Role
    let content: String
}

class OpenAIService {
    private let apiKey = "YOUR_OPENAI_API_KEY"
    private let endpoint = "https://api.openai.com/v1/chat/completions"
    let model: String = "chatgpt-4o-latest"
    
    func sendChatRequest(messages: [ChatMessage]) async throws -> String {
        
        let messageDictionaries: [[String: String]] = messages.map { msg in
            [
                "role": msg.role.rawValue,
                "content": msg.content
            ]
        }
        
        let requestBody: [String: Any] = [
            "model": model,
            "messages": messageDictionaries,
            "temperature": 0.7
        ]
        
        guard let url = URL(string: endpoint),
              let httpBody = try? JSONSerialization.data(withJSONObject: requestBody) else {
            throw NSError(domain: "Invalid Request", code: 0, userInfo: nil)
        }
        
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.setValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
        request.httpBody = httpBody
        
        let (data, _) = try await URLSession.shared.data(for: request)
        
        guard let json = try? JSONSerialization.jsonObject(with: data),
              let dict = json as? [String: Any],
              let choices = dict["choices"] as? [[String: Any]],
              let firstChoice = choices.first,
              let message = firstChoice["message"] as? [String: Any],
              let content = message["content"] as? String
        else {
            throw NSError(domain: "ChatGPT Error", code: 0, userInfo: nil)
        }
        
        return content.trimmingCharacters(in: .whitespacesAndNewlines)
    }
}

これで答えが返ってくる。

UIをつけたサンプルアプリは以下。

🐣

---

フリーランスエンジニアです。
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Core MLを使ったアプリを作っています。
機械学習関連の情報を発信しています。

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