title: NSString stringWithUTF8String return null on device, but ok on simulator
body: <p>I have a really weird problem. Basically just convert a char to nsstring and store them in an nsmutable array.</p>
  
  <p>But the code runs ok on simulator, but crash on device.</p>
  
  <p>Here is the crash code, </p>
  
  <pre><code>char t = 'A' + i;
  NSString* alphabetString = [NSString stringWithUTF8String:&amp;t]; //substringToIndex:1];
  [tempArray addObject:alphabetString];
  </code></pre>
  
  <p>Basically the stringWithUTF8String will return NULL on device, but return valid value on simulator.</p>
  
  <pre><code>The device is an iPhone 4s. 
  
  I did not see any notification of changes on NSString stringwithutf8string on iOS5 release.
  
   Thanks.
  </code></pre>