title: Sending 'const char *' to parameter of type 'const uint8_t *' error
body: <p>Am coding an iOS App, in which I have declared a string constant in a Constants file : </p>
  
  <pre><code>NSString * const kHeader = @"name,age,gender";
  </code></pre>
  
  <p>and in Constants.h</p>
  
  <pre><code>FOUNDATION_EXPORT NSString * const kHeader;
  </code></pre>
  
  <p>and am attempting to write this string to NSOutput stream in a ViewController class as:</p>
  
  <p>[outputStream write : [kHeader UTF8String] maxLength : [kHeader length]];</p>
  
  <p>This is showing a compiler warning :
  <strong>Sending 'const char *' to parameter of type 'const uint8_t *' (aka 'const unsigned char *') converts between pointers to integer types with different sign</strong></p>
  
  <p>What does this mean? How do I resolve this? Please help. Googl'ing didn't generate much useful result.</p>