title: is it safe to use [unowned self] in RxSwift Drivers?
body: <p>example:</p>
  
  <pre><code>tapGestureRecognizer.rx.event.asDriver()
      .drive(onNext: { [unowned self] _ in
          self.view.endEditing(true)
      })
      .disposed(by: disposeBag)
  </code></pre>
  
  <p>since the <code>disposeBag</code> is controlled by self, I would assume yes?</p>