title: How can I identify uppercase and lowercase characters in a string with swift?
body: <p>This is what I have so far (for testing purpose):</p>
  
  <pre><code>let string = "The quick BroWn fOX jumpS Over tHe lazY DOg"
  
  for chr in string {
      if isupper(String(chr)) {
          print(String(chr).lowercaseString)
          continue
      }
      print(chr)
  }
  </code></pre>
  
  <p>how can I test for uppercase and lowercase characters?</p>
  
  <p>I know I can call C functions from swift, but this does not seems to be correct for me.  How can I do this with swift only?</p>