merge two apps in a single app

And what is the issue ?

• coding ?
• publishing on appStore ?
• deal with payment by users ?

You could, to do it simply:

• select one of the app (to keep its appID), for instance app 1
• create an initial view that will essentially serve to direct to former app 1 and former app 2
• insert all the views and code of app 2 into app 1
• publish the new app
• when done, you can even leave old app 2 in the store or publish a new one instrcuting user to download the new app 1.

But you should explain in detail what you want to do.