ChatGPT Mac客户端开发实战：从零构建高效AI助手应用

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在开发 Mac 平台的 ChatGPT 客户端时，传统方案如 Electron 或网页封装存在明显的性能问题。Electron 应用通常占用较高内存，而网页封装则缺乏原生体验和离线功能。此外，现有解决方案往往缺少高效的对话历史管理和本地数据持久化功能，导致用户体验不佳。

在 Mac 开发中，SwiftUI 和 AppKit 是主流选择。相比之下：

SwiftUI 优势：
原生性能
与 macOS 系统深度集成
声明式 UI 开发
更好的内存管理
Electron 劣势：
较高的内存占用
性能瓶颈
包体积较大

首先创建 API 服务层，封装 OpenAI 的请求：

class OpenAIService {
    private let apiKey: String
    private let session = URLSession.shared

    init(apiKey: String) {self.apiKey = apiKey}

    func sendMessage(messages: [Message]) async throws -> String {var request = URLRequest(url: URL(string: "https://api.openai.com/v1/chat/completions")!)
        request.httpMethod = "POST"
        request.setValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")

        let body: [String: Any] = [
            "model": "gpt-3.5-turbo",
            "messages": messages.map {["role": $0.role.rawValue, "content": $0.content] },
            "temperature": 0.7
        ]

        request.httpBody = try? JSONSerialization.data(withJSONObject: body)

        let (data, _) = try await session.data(for: request)
        let response = try JSONDecoder().decode(OpenAIResponse.self, from: data)
        return response.choices.first?.message.content ?? ""
    }
}

实现重试机制和错误处理：

extension OpenAIService {func sendMessageWithRetry(messages: [Message], maxRetries: Int = 3) async throws -> String {
        var lastError: Error?

        for _ in 0..<maxRetries {
            do {return try await sendMessage(messages: messages)
            } catch {
                lastError = error
                try await Task.sleep(nanoseconds: 1_000_000_000) // 等待 1 秒
            }
        }

        throw lastError ?? NSError(domain: "", code: -1, userInfo: nil)
    }
}

创建数据模型：

struct Message: Identifiable, Codable {let id = UUID()
    let role: Role
    let content: String
    let timestamp: Date

    enum Role: String, Codable {
        case user
        case assistant
        case system
    }
}

class Conversation: ObservableObject {@Published var messages: [Message] = []

    func addMessage(_ message: Message) {messages.append(message)
    }

    func clear() {messages.removeAll()
    }
}

使用 CoreData 或文件存储实现数据持久化：

class PersistenceController {static let shared = PersistenceController()

    private let fileURL: URL

    init() {let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        fileURL = directory.appendingPathComponent("conversations.json")
    }

    func save(conversation: Conversation) throws {let data = try JSONEncoder().encode(conversation.messages)
        try data.write(to: fileURL)
    }

    func load() throws -> Conversation {let data = try Data(contentsOf: fileURL)
        let messages = try JSONDecoder().decode([Message].self, from: data)
        let conversation = Conversation()
        conversation.messages = messages
        return conversation
    }
}

请求批处理：

func batchSendMessages(messages: [[Message]]) async throws -> [String] {try await withThrowingTaskGroup(of: String.self) { group in
        for messageGroup in messages {
            group.addTask {try await self.sendMessage(messages: messageGroup)
            }
        }

        var results: [String] = []
        for try await result in group {results.append(result)
        }
        return results
    }
}

实现缓存策略：

class ResponseCache {private var cache = NSCache<NSString, NSString>()

    func get(for key: String) -> String? {cache.object(forKey: key as NSString) as String?
    }

    func set(value: String, for key: String) {cache.setObject(value as NSString, forKey: key as NSString)
    }
}