使用NSOperationQueue与NSURLSession在调用中引入依赖关系是一种糟糕的方法吗？

I have strange situation here. Assume you have task1 (NSURLSessionUploadTask) and it is uploading some huge data and user initiates task2 (NSURLSessionDataTask) which should not execute if task1 fails. On the other hand he might start another task3 which should run independently.I have strange situation here. Assume you have