title: Why does my UITableView add another section for me when I insert an entry into an exist section?
body: <p>I use NSFetchedResultController and CoreData to manage my UITableView, but I have a problem. It has really confused me for two days, and I don't know how to deal with it.</p>
  
  <p>I use two entity(Group, Contact) to store my data, and in my tableview, the contact is separated into Group, it works fine when application launch, but just after I add a contact, which is belong to one of the exist Groups, the tableview add a new section for me. That's not what I want.</p>
  
  <p>I have tried two ways and hope to fix it, but...
  the first one, I use the grp relationship of contact entity as my section separater. The result is not what I want. So I change to the second one, I add a new attribute(GName) to group my contacts, I thought maybe it's all because of grp is a relationship, so I use an attribute. It dosen't work neither.</p>
  
  <p>Pleeeease help me. any reply will be appreciate.<img src="https://i.stack.imgur.com/SGPcg.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/0ZGNT.png" alt="enter image description here"></p>