Generate different random operator on two variables in objective-c/iOS - ios

Question

I took two labels & generating random operators on them with this code:
NSArray *operators = #[#"+", #"-", #"*", #"/"];
int randomOperatorIndex = arc4random_uniform(4);
NSString *randomOperator = operators[randomOperatorIndex];
But the both of the label are generating same random operator. I want to generate different operators on the 2 labels.
Such as:
If label-1 generates "+"
then label-2 should generate "/"
But now label-1 & label-2 have same operator after generating random operator.
How can i do this on iOS with Objective-C ?

Answer 1

Try this:
// Returns an array of unique random numbers with range
-(NSMutableArray *)getRandomNumbersOfSize:(int) size from:(int) lowerLimit to:(int) higherLimit
{
NSMutableArray *uniqueNumbers = [[NSMutableArray alloc] init];
int r;
while ([uniqueNumbers count] < size)
{
r = lowerLimit + arc4random_uniform(higherLimit - lowerLimit + 1) ;
if (![uniqueNumbers containsObject:[NSNumber numberWithInt:r]])
{
[uniqueNumbers addObject:[NSNumber numberWithInt:r]];
}
}
return uniqueNumbers;
}
And in your method where you need the unique random labels:
NSArray *operators = #[#"+", #"-", #"*", #"/"];
NSMutableArray* randomOperatorIndexArray = [self getRandomNumbersOfSize:2
from:0
to:([operators count]-1)];
for(int j=0;j<[randomOperatorIndexArray count];j++)
{
NSString *randomOperator = [operators objectAtIndex:[[randomOperatorIndexArray objectAtIndex:j] intValue]];
NSLog(#"%#",randomOperator);
}