client_id mismatch when registering a new user using Sign in with Apple

Hi,

II've tried to implement Sign in with Apple (iOS 13+) in my application written in Objective C, but I keep receiving this error from my server: 

"general error_apple: error_apple - no success from apple my_app api: {\"error\":\"invalid_grant\",\"error_description\":\"client_id mismatch. The code was not issued to com.my.app.\"}"

This message is sent to me as a response from my server after I send user data from Sign in with Apple over to my server in order to register a new user account.

What might be the problem? Is it the application's fault? Or maybe it's the server's fault? Maybe it's because I'm using only authorizationCode for authorization? Should I use identityToken too? If so, how? Is the fact that I'm testing it in an emulator an issue?

client_id mismatch when registering a new user using Sign in with Apple
 
 
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