先来说说普通异步下载方法，分为POST、GET两种

/** GET请求获取数据*/+ (void)getDataWithUrl:(NSString *)strUrl finishBlock:(ECGNCNSDictionaryAndNSErrorBlock)finishBlock{    if (strUrl.length == 0) {        return;    }    NSURL *url = [NSURL URLWithString:strUrl];    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];    request.HTTPMethod = @"GET";    [request setValue:@"application/json; charset=utf-8" forHTTPHeaderField:@"Content-Type"];    NSURLSession *session = [NSURLSession sharedSession];    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {         //解析并回调数据        NSDictionary *dicData = [self dictionaryForJsonData:data];        if (finishBlock) {            finishBlock(dicData, error);        }    }];    [dataTask resume];}/** POST请求获取数据*/+ (void)postParam:(NSDictionary *)dicParam toUrl:(NSString *)strUrl finishBlock:(ECGNCNSDictionaryAndNSErrorBlock)finishBlock{    if (dicParam == nil || strUrl.length == 0) {        return;    }    NSURL *url = [NSURL URLWithString:strUrl];    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];    request.HTTPMethod = @"POST";    [request setValue:@"application/json; charset=utf-8" forHTTPHeaderField:@"Content-Type"];    request.HTTPBody = [self compactFormatDataForDictionary:dicParam];    NSURLSession *session = [NSURLSession sharedSession];    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {        //解析并回调数据        NSDictionary *dicData = [self dictionaryForJsonData:data];        if (finishBlock) {            finishBlock(dicData, error);        }    }];    [dataTask resume];}/** 将字典转换成json格式字符串,不含\n这些符号*/- (NSData *)compactFormatDataForDictionary:(NSDictionary *)dicJson{    if (![dicJson isKindOfClass:[NSDictionary class]]) {        return nil;    }        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dicJson options:0 error:nil];    if (![jsonData isKindOfClass:[NSData class]]) {        return nil;    }        return jsonData;}/** 将二进制数据转换成字典*/- (NSDictionary *)dictionaryForJsonData:(NSData *)jsonData{    if (![jsonData isKindOfClass:[NSData class]] || jsonData.length < 1) {        return nil;    }        id jsonObj = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingAllowFragments error:nil];    if (![jsonObj isKindOfClass:[NSDictionary class]]) {        return nil;    }    return [NSDictionary dictionaryWithDictionary:(NSDictionary *)jsonObj];}

 

下面说说下载文件的方法

/** 下载文件方法*/- (void)downLoadFileWithUrl:(NSString *)urlStr finishBlock:(GSNetLibTMIdAndDataAndErrorBlock)finishBlock{    if (urlStr.length == 0) {        return;    }    NSURL *url = [NSURL URLWithString:urlStr];    NSURLSession *session = [NSURLSession sharedSession];　　//构造下载任务    NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithURL:url completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {　　　　//下载成功回调，文件数据会被默认存储在一个临时目录        if (error == nil) {            if (location != nil && [location path].length > 0) {                NSString *tmpFilePath = [location path];                NSData *data = [NSData dataWithContentsOfFile:tmpFilePath];                //回调数据                if (finishBlock) {                    finishBlock(0, data, error);                }                //删除临时目录文件　　　　　　NSFileManager *fileMgr = [NSFileManager defaultManager];        　　　[fileMgr removeItemAtPath:tmpFilePath error:nil];            }        }    }];　　//执行任务    [downloadTask resume];}