NSAutoreleasePool is unavailable

I am following "Programming in Objective-C" 3^rd edition and I am having problems with the first example.

I keep getting this error:

Semantic Issue: 'NSAutoreleasePool' is unavailable: not available in automatic reference counting mode

Here is my code:

//
// main.m
// prog1 //
// Created by Steve Kochan on 1/30/11.
// Copyright 2011 ClassroomM, Inc.. All rights reserved. //

#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSLog (@"Programming is fun!");
    [pool drain];
    return 0;
}

Any insight will be greatly appreciated.