Question

I need to get random numbers that are uniform distributed.
The issue is I need every time the app start to check for some MAX number and then go randomly on all the numbers from 0 to MAX without passing twice on same number (till a round up).

Now I’m using: arc4random()%maxNumber

But that really problematic because I get lots on return even 3 times on same number in a row.

Please help.

Answer 1

This is what I finally did:

-(NSInteger)getNextRandomNumber :(NSInteger)maxNumber{

if (indexSet == nil){
    indexSet = [[NSMutableIndexSet alloc] init];
}
if ([indexSet count] >= maxNumber){
    [indexSet init];
}

NSInteger randomGen = arc4random_uniform(maxNumber);
BOOL foundNumber = FALSE;

while (!foundNumber) {
    if ([indexSet containsIndex:randomGen]){
        randomGen = arc4random_uniform(maxNumber);

    }else{
        [indexSet addIndex:randomGen];
        foundNumber = TRUE;
    }
}

return randomGen;
}

If you use it pay attention to releasing the object, Also, I think I might miss one number (not sure) on my case it doesn’t matter so…