iosobjective-carc4random

How to select range of values when using arc4random()

Can I set a range of numbers when using arc4random()? For example 50-100 only.

Solution

  • As pointed out in other posts below, it is better to use arc4random_uniform. (When this answer was originally written, arc4random_uniform was not available). Besides avoiding the modulo bias of arc4random() % x, it also avoids a seeding problem with arc4random when used recursively in short timeframes.

    arc4random_uniform(4)

    will generate 0, 1, 2 or 3. Thus you could use:

    arc4random_uniform(51)

    and merely add 50 to the result to get a range between 50 & 100 (inclusive).