title: How to get which button is clicked in RxSwift
body: <p>I have created a common action for an array of my button. I just want to get the which button is tapped.</p>
  
  <p>I have array of buttons like <code>let buttons = [UIButton(), UIButton(), UIButton(),UIButton()]</code>.</p>
  
  <pre><code>let observable = Observable.of(buttons[0].rx.tap, buttons[1].rx.tap, buttons[2].rx.tap, buttons[3].rx.tap).merge()
      observable.subscribe(onNext: {
        print("I want to find which button is tapped.")
      }).disposed(by: disposeBag)
  </code></pre>