我应该从我的模型或控制器调用我的API吗?

My question is mostly related to an architectural or design pattern for hierarchical models in Objective C. For background my app is relatively simple. In general it talks to a web service to retrieve and display things a user can follow. When someone follows something, the thing they are following is conceptually stored for access later by posting to the web service.My question is mostly related to an architectur