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iOS-AFNetworking之AFHTTPSessionMa

iOS-AFNetworking之AFHTTPSessionMa

作者: 路飞_Luck | 来源:发表于2019-04-05 22:43 被阅读0次
    序言

    AFNetworking2.0和3.0区别很大,也是因为苹果废弃了NSURLConnection,而改用了NSURLSession,AFNetworking3.0实际上只是对NSURLSession所做的操作进行了高度封装,提供更加简洁的API供编码调用。

    查看AFHTTPSessionManager.h文件,可知AFHTTPSessionManager是AFURLSessionManager的子类:

    @interface AFHTTPSessionManager : AFURLSessionManager <NSSecureCoding, NSCopying>
    
    • 实例代码 - 下载一张图片
    // 下载图片并且保存
    - (void)downloadImgAndSave {
        AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
        manager.responseSerializer = [AFHTTPResponseSerializer serializer];
        manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"image/jpeg", nil];
        
        __weak __typeof__(self) weakSelf = self;
        NSString *url = @"http://www.pptbz.com/pptpic/UploadFiles_6909/201203/2012031220134655.jpg";
        
        // 开始下载
        [manager GET:url parameters:nil progress:^(NSProgress *downloadProgress) {
            NSLog(@"progress:%lld",downloadProgress.completedUnitCount);
        } success:^(NSURLSessionDataTask *task, id responseObject) {
            NSLog(@"图片下载完成");
            __strong __typeof__(weakSelf) strongSelf = weakSelf;
            strongSelf.imgView.image = [UIImage imageWithData:(NSData *)responseObject];
        } failure:^(NSURLSessionDataTask *task, NSError *error) {
            if (error) {
                NSLog(@"%@",error.userInfo);
            }
        }];
    }
    

    运行结果

    image.png image.png
    一 GET请求调用函数分析
    • AFHTTPSessionManager.m
    - (NSURLSessionDataTask *)GET:(NSString *)URLString
                       parameters:(id)parameters
                         progress:(void (^)(NSProgress * _Nonnull))downloadProgress
                          success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success
                          failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure
    {
    
        NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"GET"
                                                            URLString:URLString
                                                           parameters:parameters
                                                       uploadProgress:nil
                                                     downloadProgress:downloadProgress
                                                              success:success
                                                              failure:failure];
    
        [dataTask resume];
    
        return dataTask;
    }
    
    - (NSURLSessionDataTask *)dataTaskWithHTTPMethod:(NSString *)method
                                           URLString:(NSString *)URLString
                                          parameters:(id)parameters
                                      uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgress
                                    downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress
                                             success:(void (^)(NSURLSessionDataTask *, id))success
                                             failure:(void (^)(NSURLSessionDataTask *, NSError *))failure
    {
        NSError *serializationError = nil;
        NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];
        if (serializationError) {
            if (failure) {
                dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{
                    failure(nil, serializationError);
                });
            }
    
            return nil;
        }
    
        __block NSURLSessionDataTask *dataTask = nil;
        dataTask = [self dataTaskWithRequest:request
                              uploadProgress:uploadProgress
                            downloadProgress:downloadProgress
                           completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {
            if (error) {
                if (failure) {
                    failure(dataTask, error);
                }
            } else {
                if (success) {
                    success(dataTask, responseObject);
                }
            }
        }];
    
        return dataTask;
    }
    
    • AFURLSessionManager.m
    - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                                   uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
                                 downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
                                completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject,  NSError * _Nullable error))completionHandler {
    
        __block NSURLSessionDataTask *dataTask = nil;
        url_session_manager_create_task_safely(^{
            dataTask = [self.session dataTaskWithRequest:request];
        });
    
        [self addDelegateForDataTask:dataTask uploadProgress:uploadProgressBlock downloadProgress:downloadProgressBlock completionHandler:completionHandler];
    
        return dataTask;
    }
    
    二 AFN的GET和POST请求实现第二层 - AFURLSessionManager
    • 实例代码 - 下载一个较大文件
    // 下载一个大文件
    - (void)downloadBigFile {
        // 1.创建配置参数
        NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
        // 2.创建会话管理者
        AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
        // 3.创建请求对象
        NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://dldir1.qq.com/qqfile/QQforMac/QQ_V5.4.0.dmg"]];
        
        // 4.创建下载任务
        /**
         * 第一个参数 - request:请求对象
         * 第二个参数 - progress:下载进度block
         *      其中: downloadProgress.completedUnitCount:已经完成的大小
         *            downloadProgress.totalUnitCount:文件的总大小
         * 第三个参数 - destination:自动完成文件剪切操作
         *      其中: 返回值:该文件应该被剪切到哪里
         *            targetPath:临时路径 tmp NSURL
         *            response:响应头
         * 第四个参数 - completionHandler:下载完成回调
         *      其中: filePath:真实路径 == 第三个参数的返回值
         *            error:错误信息
         */
        NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:^(NSProgress *downloadProgress) {
             __weak typeof(self) weakSelf = self;
            // 获取主线程,不然无法正确显示进度。
            NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];
            [mainQueue addOperationWithBlock:^{
                weakSelf.progressLbe.text = [NSString stringWithFormat:@"当前下载进度:%.2f%%",100.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount];
            }];
        } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
            
            NSURL *path = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
            return [path URLByAppendingPathComponent:response.suggestedFilename];
            
        } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
            NSLog(@"File downloaded to: %@", filePath);
        }];
        
        // 5.开启下载任务
        [downloadTask resume];
    }
    
    

    运行结果

    image.png 1.gif

    内部封装分析 AFURLSessionManager.m

    - (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request
                                                 progress:(void (^)(NSProgress *downloadProgress)) downloadProgressBlock
                                              destination:(NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
                                        completionHandler:(void (^)(NSURLResponse *response, NSURL *filePath, NSError *error))completionHandler
    {
        __block NSURLSessionDownloadTask *downloadTask = nil;
        url_session_manager_create_task_safely(^{
            downloadTask = [self.session downloadTaskWithRequest:request];
        });
    
        [self addDelegateForDownloadTask:downloadTask progress:downloadProgressBlock destination:destination completionHandler:completionHandler];
    
        return downloadTask;
    }
    

    其中self.sessionNSURLSession的一个实例对象,dataTaskWithRequest:是其创建任务的一个方式。

    @property (readonly, nonatomic, strong) NSURLSession *session;
    
    - (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request;
    

    添加代理的封装

    
    - (void)addDelegateForDownloadTask:(NSURLSessionDownloadTask *)downloadTask
                              progress:(void (^)(NSProgress *downloadProgress)) downloadProgressBlock
                           destination:(NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
                     completionHandler:(void (^)(NSURLResponse *response, NSURL *filePath, NSError *error))completionHandler
    {
        AFURLSessionManagerTaskDelegate *delegate = [[AFURLSessionManagerTaskDelegate alloc] initWithTask:downloadTask];
        delegate.manager = self;
        delegate.completionHandler = completionHandler;
    
        if (destination) {
            delegate.downloadTaskDidFinishDownloading = ^NSURL * (NSURLSession * __unused session, NSURLSessionDownloadTask *task, NSURL *location) {
                return destination(location, task.response);
            };
        }
    
        downloadTask.taskDescription = self.taskDescriptionForSessionTasks;
    
        [self setDelegate:delegate forTask:downloadTask];
    
        delegate.downloadProgressBlock = downloadProgressBlock;
    }
    

    其中setDelegate:forTask的实现

    - (void)setDelegate:(AFURLSessionManagerTaskDelegate *)delegate
                forTask:(NSURLSessionTask *)task
    {
        NSParameterAssert(task);
        NSParameterAssert(delegate);
    
        [self.lock lock];
        self.mutableTaskDelegatesKeyedByTaskIdentifier[@(task.taskIdentifier)] = delegate;
        [self addNotificationObserverForTask:task];
        [self.lock unlock];
    }
    

    其中mutableTaskDelegatesKeyedByTaskIdentifier是一个可变字典

    @property (readwrite, nonatomic, strong) NSMutableDictionary *mutableTaskDelegatesKeyedByTaskIdentifier;
    

    被调用的地方在

    - (AFURLSessionManagerTaskDelegate *)delegateForTask:(NSURLSessionTask *)task {
        NSParameterAssert(task);
    
        AFURLSessionManagerTaskDelegate *delegate = nil;
        [self.lock lock];
        delegate = self.mutableTaskDelegatesKeyedByTaskIdentifier[@(task.taskIdentifier)];
        [self.lock unlock];
    
        return delegate;
    }
    

    进而调用的是系统的代理

    - (void)URLSession:(NSURLSession *)session
          downloadTask:(NSURLSessionDownloadTask *)downloadTask
    didFinishDownloadingToURL:(NSURL *)location
    {
        AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:downloadTask];
        if (self.downloadTaskDidFinishDownloading) {
            NSURL *fileURL = self.downloadTaskDidFinishDownloading(session, downloadTask, location);
            if (fileURL) {
                delegate.downloadFileURL = fileURL;
                NSError *error = nil;
                
                if (![[NSFileManager defaultManager] moveItemAtURL:location toURL:fileURL error:&error]) {
                    [[NSNotificationCenter defaultCenter] postNotificationName:AFURLSessionDownloadTaskDidFailToMoveFileNotification object:downloadTask userInfo:error.userInfo];
                }
    
                return;
            }
        }
    
        if (delegate) {
            [delegate URLSession:session downloadTask:downloadTask didFinishDownloadingToURL:location];
        }
    }
    

    在系统NSURLSessionDelegate回调方法中,下面方法被调用多次,即将任务作为key,从字典中取出对应的delegate,再回调出去,最终回调到应用层面。

    我们看看AFURLSessionManager的方法目录结构就知道了

    • 下图是NSURLSessionDelegate方法目录结构
    image.png
    • 下图是AFURLSessionDelegate方法目录结构,和系统的NSURLSessionDelegate很像,别弄混了。
    image.png
    三 dataTaskWithRequest:completionHandler:函数详解

    说明:这个NSURLSession的API容易跟AFURLSessionManager的API混淆,参数都是一个request和一个handler block。

    • NSURLSession的API是这样的
    - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                                completionHandler:(void (^)(NSData *data, NSURLResponse *response, NSError *error))completionHandler;
    
    • 而AFURLSessionManager的API是这样的
    - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                                completionHandler:(void (^)(NSURLResponse *response, id responseObject,  NSError * error))completionHandler DEPRECATED_ATTRIBUTE;
    
    • 实例代码
    // 下载任务执行块
    - (void)dataTaskWithRequest {
        // 下载地址
        NSURL *url = [NSURL URLWithString:@"http://dldir1.qq.com/qqfile/QQforMac/QQ_V5.4.0.dmg"];
        // 创建request请求
        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
        // 设置HTTP请求头中的Range
        NSString *range = [NSString stringWithFormat:@"bytes=%zd-", self.currentLength];
        [request setValue:range forHTTPHeaderField:@"Range"];
        
        // 开始下载任务
        __weak typeof(self) weakSelf = self;
        NSURLSessionDataTask *downloadTask = [self.manager dataTaskWithRequest:request completionHandler:^(NSURLResponse *response, id responseObject, NSError *error) {
            // 下载完成
            // 清空长度
            weakSelf.currentLength = 0;
            weakSelf.fileLength = 0;
            
            // 关闭fileHandle
            [weakSelf.fileHandle closeFile];
            weakSelf.fileHandle = nil;
        }];
    }
    

    其中manager是懒加载得到的

    - (AFURLSessionManager *)manager {
        if (_manager == nil) {
            _manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
        }
        return _manager;
    }
    
    • AF内部封装实现
    - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                                completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
    {
        return [self dataTaskWithRequest:request uploadProgress:nil downloadProgress:nil completionHandler:completionHandler];
    }
    
    - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                                   uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
                                 downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
                                completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject,  NSError * _Nullable error))completionHandler {
    
        __block NSURLSessionDataTask *dataTask = nil;
        url_session_manager_create_task_safely(^{
            dataTask = [self.session dataTaskWithRequest:request];
        });
    
        [self addDelegateForDataTask:dataTask uploadProgress:uploadProgressBlock downloadProgress:downloadProgressBlock completionHandler:completionHandler];
    
        return dataTask;
    }
    
    四 总结

    AF请求操作内部实现也是和原生NSURLSession操作一样,创建task,调用resume发送请求。


    项目连接地址 - AFNetworkingDemo

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