Since you already have an existing app id you can follow the below steps to generate certificate with Push notification enabled.
- In Certificates, Identifiers & Profiles, select Identifiers.
- Under Identifiers, select App IDs.
- Select the explicit App ID, and click Edit.
- Scroll down and select the Push Notifications checkbox.
- Create Certificate under the type of SSL certificate you want to create.
- You need to generate server side and also the client side certificate with push notification enabled.
- Use the client side certificate in your app.
- And for the server side follow the below steps
a)Generate apple push notification certificate and key.ex:-apns-dev-cert.p12, apns-dev-key.p12.
b)Convert the certificate to PEM format:
openssl pkcs12 -clcerts -nokeys -out apns-dev-cert.pem -in apns-dev-cert.p12
openssl pkcs12 -nocerts -out apns-dev-key.pem -in apns-dev-key.p12
Remove the password with( use this step only for development): openssl rsa -in apns-dev-key.pem -out apns-dev-key-noenc.pem
Combine the key and cert files into apns-dev.pem, which we will use when connecting to APNS with Python: cat apns-dev-cert.pem apns-dev-key-noenc.pem > apns-dev.pem
c. Upload apns-dev.pem to your server where you will be sending out push notifications
d. Update APN_APP_ID (Apple app id) and urls in settings
- Once you have included the certificates and the codes required to support push notification on the client/server side, verify the app and upload it in itunes connect with a new version no.