title: Emit an event manually in RxSwift
body: <p>I'm a newbie in RxSwift and need a very basic help.<br/>
  Assump that I have an Observable and subscribe it like this.</p>
  
  <pre><code> let source: Observable&lt;Void&gt; = Observable.create { [weak self] observer in
  
          guard let _ = self else {
              observer.on(.Completed)
              return NopDisposable.instance
          }
  
          observer.on(.Next())
  
          return AnonymousDisposable {
  
          }
      }
  </code></pre>
  
  <p>And the subscribe like this:<br/></p>
  
  <pre><code> source.subscribeNext { () -&gt; Void in
  
      }
  </code></pre>
  
  <p>The question is: how can I emit the event to subscribeNext manually every time I need. This is like <code>rx_tap</code> behavior on <code>UIButton</code>.<br/>
  I see in the example code has something like this <code>source = button.rx_tap.asObservale()</code>. After that, every time user tap to button, there will emit an event and trigger on subscribeNext(). I also want to have that behavior but in programmatically, not from UI event.</p>