This blog includes generating the random number without repetition of number in specific range.

For this we need to take a array to store the generated number so that we can keep track that the number is already generated or not.

Here is the code-

-(void)generateRandomNumber{
    //initialize array
    arrayRandomNumber=[[NSMutableArray alloc]init];
    while (arrayRandomNumber.count<12) {
    //define the range
    NSInteger randomNumber=1+arc4random()%12;
    if (![arrayRandomNumber containsObject:[NSString stringWithFormat:@"%d",randomNumber]])       {
          [arrayRandomNumber addObject:[NSString stringWithFormat:@"%d",randomNumber]];
     }
         continue;
    }
     NSLog(@"%@",arrayRandomNumber);
}

We can define the range in the above function. e.g.- In above function - It generates random number from 1 to 12.  we can change it accordingly.