Can I determine the object type in Object-C?

Question

I have an array, arry1 that holds two kinds of objects obj1 and obj2. obj2 is a subclass of obj1. I wrote a method to sum the value of all occurances of obj1 which includes:

    int total = 0;
    for (obj1 *t in arry1){
        total += t.value;
    }

The problem is it totals both obj1 and obj2 items. It does the same if I change the for loop to be obj2 *t. So I have two questions:

1. Is there a way to determine the actual class of the current instance inside the for loop?

2. Is there a way to differentiate the two object instances in the for declaration?

Answer 1

You have to check each object and only add its value if is is of obj1 class.

int total = 0;
for (obj1 *t in arry1) {
    if ([t class] == [obj1 class])
        total += t.value;
}

Please note that it common to start class names with a capital letter. Also Obj1 would be a misleading name as it implies instance, not class.