A distribution certificate identifies your team/organization within a distribution provisioning profile and allows you to submit your app to the Apple App Store.
A .p12 file contains the certificates Apple needs in order to build and publish apps.
The steps below will guide you through the process of creating an iOS Distribution Certificate and .p12 file. To read more about certificates and how they work in Apple's App Store, please visit the iOS Dev Center and consult the official Apple documentation.
Note: These steps must be done on a Mac that you will use to submit and publish your apps to the Apple App Store. While you can transfer access to another Mac computer, we recommend following these steps on the actual machine you will use to submit apps.
1. To get the Distribution Certificate you need to first login to your Apple Developer account.
2. Click on Certificates, Identifiers & Profiles.
3. Click on add Certificate Button.
4. Select IOS Distribution (App Store and Ad Hoc).
5. It will ask you to submit a Certificate Signing Request from your MAC, Now to generate a CSR from your Mac you need to follow these steps:
a. Open Key Chain Access. On top left corner click on Key Chain, Access under the Certificate Assistant section clicks on Request a certificate from a certificate authority.
b. Fill your details and Save it to your disk.
6. Upload your CSR certificate and click okay.
7. Download your Distribution Certificate.
Now once you download your Distribution Certificate you have to export that .cer file into .p12 format to do so you need to follow these steps:
1. Open Key Chain Access on your mac and drag your Distribution Certificate in your key chain access.
2. Right-click on the certificate and Export the certificate in .P12 format.
3. Enter a password that will be used to protect the file.
NOTE:-Password is required in order to convert your website into an app.
4. Enter your Password and verify your self.