gistfile1.m

#import <Foundation/Foundation.h>
#import <sys/socket.h>

#define WEAK_BLOCK(var, __VA_ARGS__) \
    (^(typeof(var) __strong var##Strong){ \
        __weak typeof(var) var##Weak = var##Strong; \
        return ^{ \
            typeof(var) var = var##Weak; \
            __VA_ARGS__ \
        }; \
    })(var)

@interface Foo : NSObject
@property (nonatomic, copy) void (^someBlock)();
@end

@implementation Foo

- (id)init
{
    if ((self = [super init]))
    {
        [self setSomeBlock:WEAK_BLOCK(self,
                                      if (self)
                                      {
                                          NSLog(@"self %@", self);
                                          NSLog(@"%@", self->isa);
                                      }
                                      else
                                      {
                                          NSLog(@"Dieded");
                                      }
                                  )];
    }
    return self;
}

@end

int main()
{
    void (^block)(void) = nil;
    @autoreleasepool {
        Foo *foo = [[Foo alloc] init];
        block = [foo someBlock];
        block();
    }
    block();
}