How to make a Follower Counter with API 1.1 for Mac OS 10.9?


Hey there,
I am searching for hours, but I have no clue how to solve this issue:

I want to make an Application, which gets information of followers count for a certain person.
When i am using this link:
Twitter Api says: {“errors”:[{“message”:“Bad Authentication data”,“code”:215}]}

So i looked up how to use OAutha or XAutha but i didn’t understand how to use it in Objective - C.
Are there any Code Examples how to solve this?

Thanks for your help!