title: Filtering NSMutable Array of custom objects
body: <p>I have a NSMutableArray containing custom objects of type Episode. Each of these objects has multiple NSStrings as properties. Now I would like to filter the array to check if I have this episode (parsed from an XML) already and update it or create a new Episode object.</p>
  
  <p>I use the following code:</p>
  
  <pre><code>NSPredicate *predicate = [NSPredicate predicateWithFormat:@"weblink = %@", currentEpisode.weblink];
  
  NSArray* hits = [appDelegate.episodesList filteredArrayUsingPredicate:predicate];
  </code></pre>
  
  <p>currentEpisode is the episode I parsed from the XML and I want to check for, episodeList is my NSMutableArray with Episode objects. weblink is one of the NSString properties containing an URL.</p>
  
  <p>When I check on weblink everything works fine. BUT URLs in Podcastfeeds can change so I want to check on an other property called kuhid which is a unique identifier provided in the feed. 'kuhid' is also an NSString (example: 644ED540-EDCA-4D4F-882E-4B3106DDAAB3). When I check on 'kuhid' the predicate never matches and I get duplicates. 
  Both properties are NSStrings, both correctly synthesized. Same if I try one of my other NSString (e.g. title) propierties.</p>
  
  <p>Have anybody an idea why that work only with weblink and not with any of my other properties?</p>