How to Get APNS(Apple Push Notification Service) push key in order to send iOS Push Notifications.
Go to https://developer.apple.com/.
Click on the Certificates, IDs & Profiles Tab.
Go to Keys tab and click the add button.
Select the Apple Push notification service checkbox, enter a key name, then hit continue
Click Register.
Take note of the Key ID, click Download and save the .p8 file to a secure location and then click done.
Now use this .p8 File, the Key ID and the Apple Developer Team ID on the -Insert page here- page to configure iOS Push Notifications.