title: NSPredicate that ignores whitespaces
body: <p>I need to use NSPredicate to match two strings, case-insensitive,  diacritic insensitive, <strong>and whitespace-insensitive</strong>.</p>
  
  <p>The predicate would look something like this:</p>
  
  <pre><code>[NSPredicate predicateWithFormat:@"Key ==[cdw] %@", userInputKey];
  </code></pre>
  
  <p>The 'w' modifier is an invented one to express what I'd like to use.</p>
  
  <p>I can't just trim the <code>userInputKey</code> because the data-source "Key" values might have whitespaces in them too (they need those whitespaces, I can't just trim them beforehand).</p>
  
  <p>For example, given a <code>userInputKey</code> "abc" the predicate should match all of <pre>{"abc", "a b c", " a B    C   "}</pre> and so on. Given a <code>userInputKey</code>"a B C" the predicate should also match all the values in the set above.</p>
  
  <p>This can't be so hard to do, can it?</p>