title: Which UI element is suitable for drop down filter in iOS app?
body: <p>Right now i am developing app. One of it's ViewControllers has tableview with list of blog posts. I want to put some control so user can select blog's categories and then app will show posts only from those selected categories.</p>
  
  <p>I thought it would be nice if there will be "filter" button in top right corner of my app's viewcontroller. After pressing it dropdown list of category appears and user can select categories.</p>
  
  <p>What custom UI element can handle it? </p>