Can i use API in my WWDC23 Swift Student Challenge project??
API is a very generic word. Which API do you mean ?
I assume with API you refer to some external service you want to access (probably over the internet) ? If so, no you are not allowed to do this. As stated in the section Building your App playground it says:
Your creation should not rely on a network connection and any resources used in your app playground should be included locally in the ZIP file. Submissions will be judged offline.
Hope this helps.