During setup for your app, you will be asked to enter an App Identifier. This lesson explains what this is, how it is used and what format it should be in.
When developing for iOS, you need to set up a provisioning profile, and as part of this, you create an app identifier. The easiest way to do this is to make it a wildcard identifier, so that you can use the same provisioning profile for multiple apps.
You need to log in to your Apple Developer portal, and navigate to Identifiers.
1) Select Identifiers tab
2) Press (+) to add a new ID and this will take you to the "Register a New Identifier" page. Select App IDs and press continue
3) Fill in the "Description" field. This can be the name of your app or a general description such as "Testing Apps".
4) Check Wildcard and enter com.* in the bundle ID field.
6) Press "Continue". This will take you to a new page
7) Press Register
8) Select "App ID" tab again and you should see your newly created app ID
Using Your Identifier
Now you have the identifier set up, you can use it in your apps. You need to enter a unique app identifier for every app you build. It needs to be of the format
It must start with com. Provided you have a wildcard certificate as above, you will be able to change that to fit every app you want it for.