ios block 导致的循环引用

[[NSNotificationCenter defaultCenter] addObserverForName:@"UIWindowDidRotateNotification" object:self queue:nil usingBlock:^(NSNotification *note) {
        if ([note.userInfo[@"UIWindowOldOrientationUserInfoKey"] intValue] >= 3) {
            self.navigationController.navigationBar.frame = (CGRect){0, 0, self.view.frame.size.width, 64};
        }
    }];

[[NSNotificationCenter defaultCenter] removeObserver:self];