Can you point me in the right direction to how to share a calendar from one iCloud account with another iCloud account?
Hi @brower, you should be able to achieve this by logging into icloud.com. You can either share the calendar publicly or privately and Apple have the following support document with instructions on how to do so: Share a calendar on iCloud.com - Apple Support
Hope that helps 
I actually would like to know the APIs for me to be able to create an app in iOS using Swift that can allow the user to share a calendar with another user who is using a different iCloud account. Sorry for not being clear.