title: iconv with ascii // transit triggers ErrorException: "iconv(): Detected an illegal character in input string"
body: <p><em>First of all, I have to say that; I am a stranger of multilingual conversions.</em></p>
  
  <p>I have strings that i want to mb_lowercase in UTF-8 form if possible (sth like clean url), and I use </p>
  
  <pre><code>$str = iconv("UTF-8", "ASCII//TRANSLIT", utf8_encode($str));
  $str = preg_replace("/[^a-zA-Z0-9_]/", "", $str);
  $str = mb_strtolower($str);
  </code></pre>
  
  <p>to achive my requirements (an UTF8, lowercase string)</p>
  
  <p>However, when I stress that function with "çokGüŞelLl" using CocoaRestClient; I get Ã as $str (thanks to my client?) and iconv triggers an error complaining about an illegal character in input string (Ã).</p>
  
  <p>What is the problem with iconv? the str is encoded as utf8 by <code>utf8_encode($str)</code> already. How can it be an illegal character?</p>
  
  <p><em>Notes:</em>
  I read about @iconv questions here, but I think it is not a good solution to have empty database entries. </p>
  
  <hr>
  
  <p>Thanks to all answers, I will read and try to understand each of them.</p>