title: Show annotation on MKMapView based on user location
body: <p>I've problem with Objective C at the moment with developing something special.</p>
  
  <p>So - after the MKMapView is initialized and the users position is shown, I would like to implement a method to show annotations which are next to users position. I've stored all necessary points in an SQLite database in a special table. I've two fields - namely <code>lon</code>and <code>lat</code>- I think it's clear what is meant by that.</p>
  
  <p>Has anybody an idea how to show JUST those annotations which are visible at the screen to be as performant as possible. After the user scrolls the map - it should call the method again to look up in database wether there are also other points which need to be shown...</p>
  
  <p>Thank you very much in advance for your help,</p>
  
  <p>kind regards,</p>
  
  <p>Dominik</p>