Why does this snippet cause a leak?

Question

I have a class method:

+ (UIBarButtonItem*)navItemWhichAddsNewAction{
    UIBarButtonItem* addActionButton = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"icon_add"] style:UIBarButtonItemStylePlain target:nil action:nil];
    addActionButton.rac_command = [[RACCommand alloc] initWithSignalBlock:^RACSignal *(id input) {
        return [RACSignal empty];
    }];
    return addActionButton;
}

Then, in –viewDidLoad , I assign the result of this method to the right button of the navigationItem :

self.navigationItem.rightBarButtonItem = [MyClass navItemWhichAddsNewAction];

If I then profile the app with Instruments , the rac_command block above is always reported as allocated even when the view controller (and the navigation controller) is deallocated.

Why?

Answer 1

Signal doesn't complete, and leak may be caused by this. Another side-effect may be that action is not called second time because of this.