Just being random.

Generating random numbers is easy. If you want random numbers that are new each time use:
arc4random();

to set a start and range:
#define RANDOM_START 10
#define RANDOM_RANGE 20
#define randomNumber() ((arc4random() % RANDOM_RANGE) + RANDOM_START)

this will give random numbers from 10 through 29. 20 numbers starting at 10.

OR

#define randomNumber(s, r) (arc4random() % (r) +(s))

Note that a range of 5 will give 5 numbers, not 0 - 5 but 0 - 4