Array empty in a Non repeating algorithm for random numbers in Xcode with arc4random

Question

I've a problem with the generation of random values with arc4random in Xcode. I want to exclude from the random generation those number that are already picked up. This is the algorithm that I've wroten

int randomValue =  (arc4random() % numberofquest)+ 1;
int kk=1;

if (kk==1) {

//first time add the first random value
[oldquest addObject: randomValue];
    }
else {
        //control if the number is already in the vector
        for (int j=1; j<[oldquest count]; j++)
        {

            if (randomValue==oldquest[j])
            {

                randomValue =  (arc4random() % numerodomande)+ 1;
            }
            else
            {
                [oldquest addObject: randomValue];
            }
        }

}
kk=kk+1

But It doesn't work. I suppose maybe because randomvalue and the j-th object in the array are not comparable (int the first and string the second?). Can anyone help me please?

Answer 1

I'm sorry, Ares answer was almost right. You can compare two different NSNumber objects.

Here is my solution:

- (int) generateRandomNumber {
    int number = arc4random() % 100;

    if ([chosen_numbers indexOfObject:[NSNumber numberWithInt:number]]!=NSNotFound)
        number = [self generateRandomNumber];

    [chosen_numbers addObject:[NSNumber numberWithInt:number]];
    return number;
}

Since Alessandro has some trouble implementing it heres an example inside a UIViewController class. This works for 100 numbers:

#import "ViewController.h"

@implementation ViewController {
    NSMutableArray * chosen_numbers;    
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    chosen_numbers = [[NSMutableArray alloc] init];

    for(int i = 0; i<90; i++) {
        NSLog(@"number: %d",[self generateRandomNumber]);
    }
}

- (int) generateRandomNumber {
    int number = arc4random() % 100;

    if ([chosen_numbers indexOfObject:[NSNumber numberWithInt:number]]!=NSNotFound)
        number = [self generateRandomNumber];

    [chosen_numbers addObject:[NSNumber numberWithInt:number]];
    return number;
}

@end