title: Referring to weak self inside a nested block
body: <p>Suppose I already create a weak self using</p>
  
  <pre><code>__weak typeof(self) weakSelf = self;
  [self doABlockOperation:^{
          ...
  }];
  </code></pre>
  
  <p>Inside that block, if I nest another block:</p>
  
  <pre><code>[weakSelf doAnotherBlockOperation:^{
      [weakSelf doSomething];
  }
  </code></pre>
  
  <p>will it create a retain cycle? Do I need to create another weak reference to the weakSelf?</p>
  
  <pre><code>__weak typeof(self) weakerSelf = weakSelf;
  [weakSelf doAnotherBlockOperation:^{
      [weakerSelf doSomething];
  }
  </code></pre>