When creating an app, you'll need a App ID. This is used in a number of places – think of it as a unique name for your app, that will be included in our next step (creating a provisioning profile).
If you aren't already signed into your Apple iOS developer account, sign in using your authentication details.
Click Certificates, Identifiers & Profiles on the right of the screen
On the next page, click on Identifiers.
Click on the plus button at the top right
Enter a descriptive name for your App ID.
Leaving the Explicit App ID choice selected, enter a unique identifier. The usual convention here is to create a identifier of the form com.yourcompany.yourappname
Make sure to check the Push Notifications option at the bottom of this form, if you require push notifications to your App's users.
Click Continue, and confirm on the following screen, again clicking Continue/Finish.
