Can you help me in building an extension?

[Alpha2020]

In this-

Fetching from API. Please Help me

You should do network operations ( such as getting information from an API ) on another thread, or a NetworkOnMainThread exception will be thrown when your code runs, since blocks runs on the Main thread, see the example codes above to know how to run your code on a new thread, with the AsynchUtil class for example.

You can see that You should do network operations on another thread. Meaning you should not return any information from network instead use a void to put the request and event block to capture the information otherwise a NetworkOnMainThread will be raised.