嵌套nsurl dataTaskWithRequest但在完成处理程序调用之后

如何解决嵌套nsurl dataTaskWithRequest但在完成处理程序调用之后

我有这部分代码，它与“ NSURLConnection sendSynchronousRequest”一起使用，并且他们正在分派并且两个API都在其中调用而没有问题，但是，因为我要移至“ NSURLSession”，所以我要调用在complementHandler内第一个响应之后的下一个API，我是否需要为第二个API调用添加任何类型的调度？

//    dispatch_async(dispatch_get_global_queue(disPATCH_QUEUE_PRIORITY_DEFAULT,0),^{ dispatch was here

    __block Nsstring* url = @"www.google.com";
    [[LoaderService get] getRequestFrom:url completionHandler:^(TcHttpJSONResponse *response) { // first Call
        if (!response.success) {
            dispatch_async(dispatch_get_main_queue(),^{
                failBlock();
            });
            return;
        }
        
        url = [Nsstring stringWithFormat:@"www.google.com/drive"];
        [[LoaderService get] getRequestFrom:url completionHandler:^(TcHttpJSONResponse *response) { // second Call
            if (!response.success) {
                dispatch_async(dispatch_get_main_queue(),^{
                    failBlock();
                });
                return;
            }
            dispatch_async(dispatch_get_main_queue(),^{
                successBlock(transactionsArray);
            });
        }];
    }];
//    }]; //end of dispatch

在LoaderService中

- (void)getRequestFrom:(Nsstring *)url completionHandler:(void (^)(TcHttpJSONResponse *response))completionHandler {
    NSURLSession *session = [NSURLSession sharedSession];
    [[session dataTaskWithRequest:[TcHttpHelper getRequestFromUrlWithAuthorizationToken:url token:[self getAuthToken]]
            completionHandler:^(NSData *data,NSURLResponse *response,NSError *error) {
        completionHandler([[TcHttpJSONResponse alloc] initWithResponse:data urlResponse:(NSHTTPURLResponse*)response error:error]);
    }] resume];
}