random - Objective-C: Modulo bias

Question

Using:

value = arc4random() % x

How can I avoid or eliminate modulo bias?

At least according to Wikipedia, modulo bias is an issue when programming games of chance.

Answer 1

Use arc4random_uniform(x). This does it for you.

According to the man page:

arc4random_uniform() will return a uniformly distributed random number less than upper_bound. arc4random_uniform() is recommended over constructions like arc4random() % upper_bound as it avoids "modulo bias" when the upper bound is not a power of two.