Compare NSString in switch satement

I have a if statement comparing NSString like this :

NSString *str = @"whatevstring";

NSArray *array = @[@"string1",@"string2",@"string3"];

if ([str isEqualToString:@"string1"] ){
  //str == string1
} else if ([str isEqualToString:@"string2"]){
  //str == string2
} else if ([str isEqualToString:@"string3"]){
  //str == string3
}

and I would like it alternates with switch statement,

this is how I do it:

int compareInt;

for (int i = 0; i < 4; i++) {
    if ([segue.identifier isEqualToString:[array objectAtIndex:i]]) {
        compareInt = i;
        break;
    //well, I supposed not to use any if statement...
    }
}

switch (compareInt) {
    case 0:
        //str == string1;
        break;
    case 1:
        //str == string2;
        break;
    case 2:
        //str == string3;
        break;   
    default:
        break;
}

is there a better way to do this with switch statement?

or is if statement the only and best choice when it comes up with comparison in objective-C?

any suggestion welcome!