Best way to generate NSData object with random bytes of a specific length?

Question

If I create a new NSData object of a specific size using dataWithBytes:length:, what is the most efficient way to create the input bytes (20 Mb worth) of random characters, pref

Answer 1

Use arc4random_buf to fill the buffer with random bytes

Obj-C

+ (nullable NSData *)radomDataOfSize:(size_t)sizeInBytes
{
    void *buff = malloc(sizeInBytes);
    if (buff == NULL) {
        return nil;
    }
    arc4random_buf(buff, sizeInBytes);

    return [NSData dataWithBytesNoCopy:buff length:sizeInBytes freeWhenDone:YES];
}