I published an app which has about 10 different tabs. I got an email from a buyer saying that he edits those tabs to the order that he/she would like it to be. The problem is that it doesn't save it for the next launch. How do I get it to save the tab edits?
You mean the next time he uses the application, you want the values in the tabs to default to what he entered the previous time?
If so, you'd need to save the information to a database, or if a web app, to a cookie perhaps, and then when the application starts and the user is authenticated you'd fill in that information from the cookie/database.
A common approach is to use a config file that stores the count/order of tabs open (with possibly more info). It has the advantage that is something gets foobar'd in this area the user can be guided to manually edit the file.
I don't know xcode, but the general idea would be that when your app closes you save an id for each tab with its current index within the tab control. Then on loading your app you iterate through the list and set each tab's index to the saved value (which you load upon startup.)
Of course, on the initial run when there is no prior order your default order takes precedence.