title: How to check whether an entity already exists in persistent store
body: <p>I am very new to the Core Data programming. I have a question to which I hope to get some clarification.</p>
  
  <p>Supposing I have an NSManagedObject called <code>Company</code>, with the following attributes:</p>
  
  <ul>
  <li>companyName</li>
  <li>companyEmail</li>
  <li>companyPhoneNo</li>
  <li>companyUserName</li>
  <li>companyPassword</li>
  </ul>
  
  <p>In this object the <code>companyName</code> attribute is indexed.</p>
  
  <p>So, my question is, how can I make sure that there will be only entry with same companyName, companyEmail, companyPhoneNo, companyUserName and companyPassword?</p>
  
  <p>Do I need to make a request to check if there are any records with the same attribute values or is a simple check with the object id sufficient?</p>
  
  <p>Thanks.</p>