title: Sha256 in Objective-C for iPhone
body: <p>When I use this code to create a sha256 of a string</p>
  
  <pre><code>unsigned char hashedChars[32];
  NSString *inputString;
  inputString = [NSString stringWithFormat:@"hello"];
  NSData * inputData = [inputString dataUsingEncoding:NSUTF8StringEncoding];
  CC_SHA256(inputData.bytes, inputData.length, hashedChars);
  </code></pre>
  
  <p>It returns the hash correctly, but I need to insert a string like this <strong>\x00\x25\x53</strong> and in this case, the function returns a sha256 of empty string because the specified encoding cannot be used to convert the receiver.</p>
  
  <p>Now, my question is:How to insert this special characters for generate a correct hash? Thanks</p>