random BOOLs in an efficient way for cocos2d

you can do something like this:

+(BOOL) getYesOrNo
{
    int tmp = (arc4random() % 30)+1;
    if(tmp % 5 == 0)
        return YES;
    return NO;
}

You should use arc4random for random number generator.

#include <stdlib.h>

     u_int32_t
     arc4random(void);

The arc4random() function uses the key stream generator employed by the arc4 cipher, which uses 8*8 8 bit S-Boxes. The S-Boxes can be in about (2*1700) states. The arc4random() function returns pseudo- random numbers in the range of 0 to (2*32)-1, and therefore has twice the range of rand and random.

-(BOOL)foo4random
{
u_int32_t randomNumber = (arc4random() % ((unsigned)RAND_MAX + 1));
if(randomNumber % 5 ==0)
    return YES;
return NO;

}

For more information on arc4random type

man arc4random

on terminal.