title: Objective-C NSMutableArray - foreach loop with objects of multiple classes
body: <p>I have the NSMutableArray *children in the datastructure-class "Foo" which is the superclass of many others, like "Bar1" and "Bar2".
  That array stores Bar1 and Bar2 objects to get a tree-like recursive parent-children-structure of subclasses from Foo.
  To access the objects in the array, I loop through them using the foreach loop in Objective-C:</p>
  
  <pre><code>for(Foo *aFoo in children) {
      ...
  }
  </code></pre>
  
  <p>But often I only need to loop through the objects in the array that have a certain class, in this case I want to perform a task for each object of the class Bar1 in the array children. Using for(Bar1 *anObject in children) again loops  through ALL objects and not only the ones with the class Bar1. Is there a way to achieve what I need?</p>