title: Generate SHA256 hash in Objective-C
body: <p>So I need to generate a Sha256 password in Objective-C, and can't figure out for the life of me how to do it! Is there something easy I'm just missing?</p>
  
  <p>I've tried implementing the following method (which was written for iPhone, but I figured maybe it'd work cross-platform, as some Objective-C code does)</p>
  
  <pre><code>-(NSString*)sha256HashFor:(NSString*)input
  {
      const char* str = [input UTF8String];
      unsigned char result[CC_SHA256_DIGEST_LENGTH];
      CC_SHA256(str, strlen(str), result);
  
      NSMutableString *ret = [NSMutableString stringWithCapacity:CC_SHA256_DIGEST_LENGTH*2];
      for(int i = 0; i&lt;CC_SHA256_DIGEST_LENGTH; i++)
      {
          [ret appendFormat:@"%02x",result[i]];
      }
      return ret;
  }
  </code></pre>
  
  <p>But that just spat out errors about CC_SHA256_DIGEST_LENGTH being an undeclared identifier.</p>