We can't simply cross check the index value with nil! <NSNotFound>

gistfile1.m

NSArray *array = @[@(1),@(2),@(3)];
NSInteger index = [array indexOfObject:@(4)];
/** @abstract: we can’t compare the index and also we can’t able to check whether it is a nil value or not?
    Coz, its a Long Long integer. if you print the index on debugger window, you will get this value:  9223372036854775807
    Thats why we are checking with NSNotFound
    If you don't don the defence check you will crash. Its safety check!.
*/
    if(index == NSNotFound) {
        // index value is not found !
        // Use the NSAssert for handling the value or !value here.
    }