// Returns array of NSNumber objects

+ (NSArray *)randomNumbersArrayOfLength:(int)length minValue:(int)minValue maxValue:(int)maxValue
{
    if (length > 0) {

        NSMutableArray *randomNumbersArray = [[NSMutableArray alloc] initWithCapacity:length];
        if (!minValue) minValue = 0;
        if (!maxValue) maxValue = length * 10;
        if (minValue > maxValue) {
            // if minValue is bigger than maxValue, swap numbers
            NSLog(@"Random Numbers: supposed minimum value given is bigger than maximum value. Swapping values.");

            int max = minValue;
            minValue = maxValue;
            maxValue = max;

            NSLog(@"New values:");
            NSLog(@"Min: %i", minValue);
            NSLog(@"Max: %i", maxValue);
        }

        for (int i = 0; i < length; i++) {
            [randomNumbersArray addObject:[NSNumber numberWithInt:minValue + arc4random() % (maxValue - minValue + 1)]];
        }

        return randomNumbersArray;
    }

    return nil;
}