How to create custom contextual filter for views using views api.

I have a custom table which is having some statistics data about the user. The user id is also stored in the table. I managed to get the results using views api, Now I would like to use the contextual filter on the logged-in user, this is where I got interrupted. The contextual links are empty, its not showing any filters I can use of. How do I get contextual filters working using views api?

How to create custom contextual filter for views using views api.

I have a custom table which is having some statistics data about the user. The user id is also stored in the table. 

I managed to get the results using views api, Now I would like to use the contextual filter on the logged-in user, this is where I got interrupted. The contextual links are empty, its not showing any filters I can use of. How do I get contextual filters working using views api?