基于AFNetwork3.0的网络请求，下载及上传

1.项目中引入AFNetwork，新建一个继承于NSObject的类Network，并在.h中定义一下方法：

//网络请求
- (void)networkWithURL:(NSString *)url
             parameter:(NSDictionary *)paraDic
               success:(void(^)(id obj))success
                  fail:(void(^)(NSError *error))fail;

//文件上传
- (void)networkWithURL:(NSString *)url
                   pic:(UIImage *)image
             parameter:(NSDictionary *)paraDic
               success:(void (^)(id obj))success
                  fail:(void (^)(NSError *error))fail;

//下载
//progressBlock 下载进度
//completeBlock 成功回调
- (void)downloadWithURL:(NSString *)url
               progress:(void (^)(float percent))precentBlock
               complete:(void (^)(NSString *fileName))completeBlock
                fileUrl:(void(^)(NSURL *fileUrl))fileUrl;

2.定义方法后，在.m中首先实现网络请求功能

- (void)networkWithURL:(NSString *)url parameter:(NSDictionary *)paraDic success:(void (^)(id))success fail:(void (^)(NSError *))fail {
    //NSURLSession 配置信息
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
    //创建请求
    NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:url parameters:paraDic constructingBodyWithBlock:nil error:nil];
    NSURLSessionDataTask *dataTask = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
        if (error) {
            fail(error);
        } else {
            success(responseObject);
        }
    }];
    //开启任务
    [dataTask resume];
}

3.文件上传功能，上传文件以图片为例

//图片以及其他信息上传
- (void)networkWithURL:(NSString *)url pic:(UIImage *)image parameter:(NSDictionary *)paraDic success:(void (^)(id obj))success fail:(void (^)(NSError *error))fail {
    //NSURLSession 配置信息
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
    //创建请求
    NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:url parameters:paraDic constructingBodyWithBlock:^(id<AFMultipartFormData>  _Nonnull formData) {
        //在这里提交图片/视频/音频文件
        //把图片转为NSData
        //第一个参数是 data
        //第二个参数是服务器提供的字段名
        //第三个字段随意
        //第四个参数文件类型
        NSData *data = UIImageJPEGRepresentation(image, 0.5);
        [formData appendPartWithFileData:data name:@"iconfile" fileName:[NSString stringWithFormat:@"%f.png", [[NSDate date] timeIntervalSince1970]] mimeType:@"PNG/JPEG/JPG"];
    } error:nil];
    NSURLSessionDataTask *dataTask = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
        if (error) {
            fail(error);
        } else {
            success(responseObject);
        }
    }];
    //开启任务
    [dataTask resume];
    
}

4.下载功能

- (void)downloadWithURL:(NSString *)url
               progress:(void (^)(float percent))precentBlock
               complete:(void (^)(NSString *fileName))completeBlock
                fileUrl:(void(^)(NSURL *fileUrl))fileUrl {
    //在cache文件下, 创建存储MP3文件的的文件夹
    //建立存储路径/Download
    NSString *mp3FilePath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject] stringByAppendingPathComponent:@"Download"];
    //判断文件夹是否存在
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if ([fileManager fileExistsAtPath:mp3FilePath]) {
        
    } else {
        //创建文件夹
        [fileManager createDirectoryAtPath:mp3FilePath withIntermediateDirectories:YES attributes:nil error:nil];
    }
    NSString *fileName = url.md5;
    //文件下载成功后存储路径
    NSString *filePath = [mp3FilePath stringByAppendingPathComponent:fileName];
    //如果文件已下载, 停止下载 
    if ([fileManager fileExistsAtPath:filePath]) {
        [[[UIAlertView alloc] initWithTitle:@"提示" message:@"文件已下载" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:nil, nil] show];
        return;
    }
    
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
    //创建request
    //POST请求, 用 [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:]

    //如果是GET请求, 用下面的方法
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];
    //创建下载任务
    NSURLSessionDownloadTask *task = [manager downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {
        //这里返回下载进度
        dispatch_async(dispatch_get_main_queue(), ^{
            precentBlock(downloadProgress.completedUnitCount / (downloadProgress.totalUnitCount / 1.0));
        });
    } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
        //要求返回文件存储的路径
        //临时文件
        NSString *tempPath = NSTemporaryDirectory();
        return [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/%@", tempPath, fileName]];
    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePt, NSError * _Nullable error) {
        //下载完成
        if (!error) {
            //先把临时文件移到download文件夹
            //然后删除临时文件
            //成功回调
            [fileManager copyItemAtURL:filePt toURL:[NSURL fileURLWithPath:filePath] error:nil];
            [fileManager removeItemAtURL:filePt error:nil];
            completeBlock(fileName);
        } else {
            NSLog(@"网络请求失败");
        }
    }];
    [task resume];
}