title: NSMutableURLRequest - Why will it not set header values with a regular NSString?
body: <p>It appears that setting values for a header field (i.e. @"Content-Type") will not take the value unless it is base64 encoded. The method docs say it takes a plain NSString, so it really shouldn't matter. However, encoding it this way seems to render useless the value for the post request...right? 
  See below:</p>
  
  <pre><code>[req setHTTPBody:allData];
       [req setHTTPMethod:@"POST"];
       [req setValue:@"multipart/related; "
        "boundary==_27da60ee13b84794c5873572c502aaae\n" forHTTPHeaderField:@"Content-Type"]; 
  
       NSLog(@"\n\n\t\t===headerField content-type===\n\n%@", [req valueForHTTPHeaderField:@"Content-Type"]);
  </code></pre>
  
  <p>Yields:</p>
  
  <pre><code>2010-12-22 09:53:23.008 uploadXMLText[96009:207] 
  
            ===headerField content-type===
  
  (null)
  </code></pre>
  
  <p>But if I encode the value string @"multipart..." to base64:</p>
  
  <p>Yields:</p>
  
  <pre><code>2010-12-22 10:06:37.185 uploadXMLText[96234:207] 
  
            ===headerField content-type===
  
  bXVsdGlwYXJ0L3JlbGF0ZWQ7IGJvdW5kYXJ5PT1fMjdkYTYwZWUxM2I4NDc5`*
  </code></pre>
  
  <p>Any ideas anyone?</p>
  
  <p>Thanks! </p>
  
  <p>Me</p>