An Objective-C Primer(Chapter 2 of Objective-C Phrasebook)

#import <Foundation/Foundation.h>

int(^getCounter(void))(void)
{
    __block int counter;
    int(^block)(void)=^(void){ return counter++; };
    return _Block_copy(block);
}

int main (void) 
{
    int (^block)(void) = getCounter();
    block();
    block();
    NSCAssert(block() == 2, @"Block counted incorrectly");
    int(^block2)(void) = getCounter();
    block2(); 
    block2();
    NSCAssert(block2() == 2, @"Block didn't start from 0");
    NSLog(@"%d", block2());
    return 0;
}