main.m

//
//  main.m
//  Foo
//
//  Created by leafduo on 2/11/13.
//  Copyright (c) 2013 leafduo.com. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "NSMutableArray+Pop.h"

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        NSMutableArray *array = [@[@1, @2, @3] mutableCopy];
        NSLog(@"%@", [array pop]);
        NSLog(@"%@", array);
    }
    return 0;
}

NSMutableArray+Pop.h

//
//  NSMutableArray+Pop.h
//  Foo
//
//  Created by leafduo on 2/11/13.
//  Copyright (c) 2013 leafduo.com. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSMutableArray (Pop)

- (id)pop;

@end

NSMutableArray+Pop.m

//
//  NSMutableArray+Pop.m
//  Foo
//
//  Created by leafduo on 2/11/13.
//  Copyright (c) 2013 leafduo.com. All rights reserved.
//

#import "NSMutableArray+Pop.h"

@implementation NSMutableArray (Pop)

- (id)pop {
    id obj = [self.lastObject copy];
    [self removeObject:self.lastObject];
    return obj;
}

@end