Here’s an Objective C method that’ll return a SHA512 hex of a given string:

-(NSString*) sha512:(NSString*)input {
    const char *cstr = [input cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:input.length];
    
    uint8_t digest[CC_SHA512_DIGEST_LENGTH];
    
    CC_SHA512(data.bytes, data.length, digest);
    
    NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA512_DIGEST_LENGTH * 2];
    
    for(int i = 0; i < CC_SHA512_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x", digest[i]];
    
    return output;
    
}

You'll need to include:

    #include