Alamofire-细节

一、动态适配adapter

• RequestAdapter协议
• adapt Alamofire没有实现，需要自己实现

public protocol RequestAdapter {
    func adapt(_ urlRequest: URLRequest) throws -> URLRequest
}

• 1: request 处理
• 2: request 重定向

        SessionManager.default.adapter = DYZAdapter()
        SessionManager.default.request(urlStr, method: .get, parameters: ["username":"dyz","password":"123"]).response { (response) in
            debugPrint(response)
        }

class DYZAdapter: RequestAdapter {
    func adapt(_ urlRequest: URLRequest) throws -> URLRequest {
        // 1: request 处理
//        var request = urlRequest
//        request.setValue("Dyztoken", forHTTPHeaderField: "dyztoken")
//        return request
        
        // 2: request 重定向
        let newUrlRequest = URLRequest.init(url: URL(string: "http://www.douban.com/j/app/radio/channels")!)
        return newUrlRequest
    }
}

• 实例1: 判断token，没有，先请求token，然后再请求，不浪费每一次请求

二、验证和重试

• validate 验证

        SessionManager.default.request(myGetUrlString, method: .get, parameters: ["username":"dyz","password":"123"]).response { (response) in
            debugPrint(response)
            }.validate { (request, response, data) -> Request.ValidationResult in
                guard let _ = data else {
                    return .failure(NSError.init(domain: "dyz", code: 10086, userInfo: nil))
                }
                let code = response.statusCode
                if code == 404 {
                    return .failure(NSError.init(domain: "dyz", code: 10090, userInfo: nil))
                }
                return .success
        }

• retrier
  RequestRetrier 协议

public protocol RequestRetrier {
    func should(_ manager: SessionManager, retry request: Request, with error: Error, completion: @escaping RequestRetryCompletion)
}

        SessionManager.default.retrier = DYZRetrier()
        SessionManager.default.request(urlStr, method: .get, parameters: ["username":"dyz","password":"123"]).response { (response) in
            debugPrint(response)
            }.validate { (request, response, data) -> Request.ValidationResult in
                guard let _ = data else {
                    return .failure(NSError.init(domain: "dyz", code: 10086, userInfo: nil))
                }
                let code = response.statusCode
                if code == 404 {
                    return .failure(NSError.init(domain: "dyz", code: 10090, userInfo: nil))
                }
                return .success
        }

class DYZRetrier: RequestRetrier {
    func should(_ manager: SessionManager, retry request: Request, with error: Error, completion: @escaping RequestRetryCompletion) {
        print("manager = \(manager)")
        print("request = \(request)")
        print("error = \(error)")
        completion(true,1)
        // 一定要有出口，不然持续递归就会发生很严重的影响
//        completion(false,0)
    }
}

三、TaskDelegate里的queue逻辑

• startRequestsImmediately默认值为true
SessionManager.default.startRequestsImmediately = false

• operationQueue初始化

    init(task: URLSessionTask?) {
        _task = task

        self.queue = {
            let operationQueue = OperationQueue()

            operationQueue.maxConcurrentOperationCount = 1
            operationQueue.isSuspended = true
            operationQueue.qualityOfService = .utility

            return operationQueue
        }()
    }

• 请求完成 queue.isSuspended = false

    @objc(URLSession:task:didCompleteWithError:)
    func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
        if let taskDidCompleteWithError = taskDidCompleteWithError {
            taskDidCompleteWithError(session, task, error)
        } else {
            if let error = error {
                if self.error == nil { self.error = error }

                if
                    let downloadDelegate = self as? DownloadTaskDelegate,
                    let resumeData = (error as NSError).userInfo[NSURLSessionDownloadTaskResumeData] as? Data
                {
                    downloadDelegate.resumeData = resumeData
                }
            }

            queue.isSuspended = false
        }
    }

四、Timeline

requestStartTime 初始化请求的时间
initialResponseTime 从服务器接收或发送第一个字节的时间
requestCompletedTime 请求完成的时间
serializationCompletedTime 响应序列化完成的时间
latency 从请求开始到服务器的初始响应的时间间隔(以秒为单位)、TimeInterval 秒、secs 秒
requestDuration 从请求开始到请求完成的时间间隔(以秒为单位)
serializationDuration 从请求完成到响应序列化完成的时间间隔(以秒为单位)
totalDuration 从请求开始到完成响应序列化的时间间隔(以秒为单位)

五、Result

public enum Result<Value> {
    case success(Value)
    case failure(Error)

    public var isSuccess: Bool { get }
    public var isFailure: Bool { get }
    public var value: Value? { get }
    public var error: Error? { get }
}

枚举