title: Added pod files and pushed. How to undo? how to use gitignore in Xcode & github?
body: <p>This is a two part question:
  1) I have added committed and pushed all pod files to github. Is there a way I can remove them and not push them again to github?</p>
  
  <p>2) I know gitignore can help, but I don't know how to use it. Can anyone please walk me through the process of using gitignore? </p>
  
  <p>so I think what I can do is, get the project from github, add gitignore, and then push again. is that correct? </p>
  
  <p>Please help, new to github &amp; Xcode. </p>