An example of how enumerators can be used to separate the collection of objects from the processing code. It's worthwhile also noting that enumerators can be created to return objects in any desired order.

bareEnumeratorDemo.mm

#import <Foundation/Foundation.h>

void enumerate(NSEnumerator *enumerator, NSString *name) 
{
  id obj = [enumerator nextObject];
	
	NSLog(@"Enumerating using '%@'...", name);
	
	while (obj) 
	{
		NSLog(@"%@", obj);
		obj = [enumerator nextObject];	
	}
}

int main(int argc, char *argv[]) 
{
	@autoreleasepool 
	{
		
		NSArray *myArray = @[@"alpha", @"beta", @"gamma", @"delta"];
	
		enumerate([myArray objectEnumerator], @"Forwards");
		enumerate([myArray reverseObjectEnumerator], @"Backwards");
		
	}
}