title: Why can't I use startActivityForResult in Kotlin?
body: <p>I hope to open a activity for result in Kotlin.</p>
  
  <p>I have read the artical <a href="https://stackoverflow.com/questions/45225642/cant-call-startactivityforresult-in-anko">Can&#39;t Call StartActivityForResult in Anko</a></p>
  
  <p>So I convert AppCompatActivity as  Activity</p>
  
  <p>But the code  <code>(mContext as Activity).startActivityForResult&lt;UIAddEditBackup&gt;(requestCode = 1, "id" to 2L)</code>  doesn't run yet, why?</p>
  
  <p><strong>My Code</strong></p>
  
  <pre><code>class UIMain : AppCompatActivity() {
  
      private lateinit var mContext: Context
  
      override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)
          setContentView(R.layout.layout_main)
           mContext = this
           btnExit.setOnClickListener {
              startActivity&lt;UIAddEditBackup&gt;("id" to 2L)  //OK
              (mContext as Activity).startActivityForResult&lt;UIAddEditBackup&gt;(requestCode = 1, "id" to 2L) //Error          
          }
      }
  }
  </code></pre>