OBJC: HMAC creation - Pass Key and Data as String

OBJC: HMAC creation - Pass Key and Data as String.txt

-(NSString*)generateHMACwith :(NSString* )key :(NSString*)data{
    const char *cKey  = [key cStringUsingEncoding:NSUTF8StringEncoding];
    const char *cData = [data cStringUsingEncoding:NSUTF8StringEncoding];
    unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];
    CCHmac(kCCHmacAlgSHA256,
           cKey,
           strlen(cKey),
           cData,
           strlen(cData),
           cHMAC);
    NSData *HMAC = [[NSData alloc] initWithBytes:cHMAC
                                          length:sizeof(cHMAC)];
    NSString *hash = [HMAC base64EncodedStringWithOptions:0];
    return hash;
}