title: Is it safe to change the AppID Prefix between updates?
body: <p>I am trying to understand the role of the first part of the AppID for iOS apps.
  This part was formerly known as the "Bundle Seed ID", but is now often referred to as the AppID Prefix.</p>
  
  <p>A while ago (iOS 5?), Apple made some changes in both their portal and their documentation and started to recommend using the "Team ID" (unique per developer account) as the AppID Prefix. This is simple and straightforward for new developers with new apps.</p>
  
  <p>But what is the the best practice for handling existing apps with regards to the AppID prefix?
  I know that it is not possible to change BundleID (= the second part of the AppID) between two app versions, but <strong>is it safe to change the prefix between app versions?</strong></p>
  
  <p>Note that I am not referring to replacing a "wildcard AppID", e.g. ABC1234567.*, to an explicit AppID using the same prefix, e.g. ABC1234567.com.mycompany.myapp. There is tons of information about this (most of it outdated, though). I am thinking about changing the complete AppID, e.g. ABC1234567.com.mycompany.myapp, for an existing app by replacing the prefix with my Team ID, e.g. DEF7654321.com.mycompany.myapp.</p>
  
  <p>I think I have read somewhere that it should be OK to change the prefix for existing apps, except in the special case that the app is using the keychain to store data. If this is true, the easiest way to handle the prefix for existing apps would be to migrate to the new Team ID when it's time to release next update. When all my apps are migrated, I can continue using the Team ID (as Apple recommends for new apps) and finally forget about all this mess.
  <strong>Can anyone confirm this?</strong></p>
  
  <p>If you can shed some more lights upon the concept of the AppID prefix, and what it is actually used for on an iOS device (except the keychain which I already know about), I would be happy if you could write a comment. Perhaps we could build up the full understanding of this by adding bits and pieces from different sources. Sadly, the Apple documentation is very thin in this area.</p>
  
  <p>(There is another similar question: <a href="https://stackoverflow.com/q/2575552/824515">Can I change the Bundle Identifier in my app after it&#39;s been approved?</a> But that is mainly focusing on the BundleID, i.e. the second part of the AppID, so this is not a duplicate, even though some of the answers and comments are touching upon this topic.)</p>