iOS Alamofire库的使用

Alamofire 是 iOS/macOS 开发中最常用的网络请求库之一，基于 Swift 编写，封装了 URLSession，提供了链式调用、JSON 解析、文件上传/下载等高级功能。以下是 Alamofire 的具体用法和示例，涵盖常见场景。

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1. 安装 Alamofire
   通过 CocoaPods 安装
   在 Podfile 中添加：

pod 'Alamofire', '~> 5.8'

然后运行 pod install。

通过 Swift Package Manager (SPM)
在 Xcode 的 File > Add Packages 中输入：

https://github.com/Alamofire/Alamofire.git 

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2. 基本用法
   (1) 发起 GET 请求

import Alamofire AF.request("https://httpbin.org/get").response { response in switch response.result {case .success(let data):print("请求成功: \(String(describing: data))")case .failure(let error):print("请求失败: \(error)")}
}

(2) 带参数的 GET 请求

let parameters = ["page": 1, "limit": 10]AF.request("https://httpbin.org/get", parameters: parameters).responseJSON { response in switch response.result {case .success(let json):print("JSON 数据: \(json)")case .failure(let error):print("请求失败: \(error)")}
}

(3) 发起 POST 请求

let parameters = ["username": "test", "password": "123456"]AF.request("https://httpbin.org/post", method: .post, parameters: parameters).responseJSON { response in switch response.result {case .success(let json):print("POST 成功: \(json)")case .failure(let error):print("POST 失败: \(error)")}
}

(4) 使用 Encodable 发送 JSON
如果你的参数是 Encodable 对象（如 struct），可以这样：

struct User: Encodable {let name: String let age: Int 
}let user = User(name: "John", age: 25)AF.request("https://httpbin.org/post", method: .post, parameters: user, encoder: JSONParameterEncoder.default).responseJSON { response in switch response.result {case .success(let json):print("POST 成功: \(json)")case .failure(let error):print("POST 失败: \(error)")}
}

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3. 高级用法
   (1) 文件上传

let fileURL = Bundle.main.url(forResource: "test", withExtension: "jpg")!AF.upload(fileURL, to: "https://httpbin.org/post").uploadProgress { progress in print("上传进度: \(progress.fractionCompleted)")
}.responseJSON { response in switch response.result {case .success(let json):print("上传成功: \(json)")case .failure(let error):print("上传失败: \(error)")}
}

(2) 文件下载

let destination: DownloadRequest.Destination = { _, _ in let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]let fileURL = documentsURL.appendingPathComponent("image.jpg")return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
}AF.download("https://httpbin.org/image/jpeg", to: destination).response { response in if let filePath = response.fileURL?.path {print("文件已保存到: \(filePath)")}
}

(3) 请求头 & 认证

let headers: HTTPHeaders = ["Authorization": "Bearer YOUR_TOKEN","Accept": "application/json"
]AF.request("https://httpbin.org/headers", headers: headers).responseJSON { response in switch response.result {case .success(let json):print("带 Header 的请求: \(json)")case .failure(let error):print("请求失败: \(error)")}
}

(4) 拦截请求（RequestInterceptor）
可以统一处理认证、重试等逻辑：

struct AuthInterceptor: RequestInterceptor {func adapt(_ urlRequest: URLRequest, for session: Session, completion: @escaping (Result<URLRequest, Error>) -> Void) {var request = urlRequest request.setValue("Bearer YOUR_TOKEN", forHTTPHeaderField: "Authorization")completion(.success(request))}
}let session = Session(interceptor: AuthInterceptor())
session.request("https://httpbin.org/headers").responseJSON { response in // 处理响应 
}

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4. 错误处理
   Alamofire 提供了详细的错误信息：

AF.request("https://httpbin.org/status/404").validate().response { response in if let error = response.error {if let statusCode = response.response?.statusCode {print("HTTP 状态码错误: \(statusCode)")}print("详细错误: \(error.localizedDescription)")}
}

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5. 结合 Combine（iOS 13+）
   Alamofire 支持 Combine，可以轻松集成到响应式编程中：

import Combine AF.request("https://httpbin.org/get").publishDecodable(type: ResponseModel.self).sink { completion in if case .failure(let error) = completion {print("请求失败: \(error)")}} receiveValue: { response in print("收到数据: \(response.value)")}.store(in: &cancellables)

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总结

功能	示例
GET 请求	AF.request("https://example.com/get")
POST 请求	AF.request("https://example.com/post", method: .post, parameters: params)
文件上传	AF.upload(fileURL, to: "https://example.com/upload")
文件下载	AF.download("https://example.com/file", to: destination)
请求头	headers: HTTPHeaders = ["Authorization": "Bearer token"]
错误处理	response.validate().responseJSON { ... }

Alamofire 让网络请求变得更简单，适用于大多数 HTTP 请求场景。建议结合 Codable 解析 JSON 数据，提升代码可维护性。