title: NSPredicate in swift for empty string
body: <p>Swift 4.2 iOS 11.x</p>
  
  <p>Trying to read the records in a iCloud database that have a lineOwner field set, but struggling to create an NSPredicate that works!</p>
  
  <p>This looks ok, but doesn't parse.</p>
  
  <pre><code>let predicate = NSPredicate(format: remoteAttributes.lineOwner + " != %@",0)
  </code></pre>
  
  <p>I get an invalid predicate error message [and a nasty crash into the bargain]. Spend a couple of hours on this and losing the will to live. </p>
  
  <p>If I print out the database I see this.</p>
  
  <p><a href="https://i.stack.imgur.com/vCKCo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vCKCo.png" alt="enter image description here"></a></p>