title: How to call ViewChild in runtime?
body: <p>In Angular2 ,
  I want to find my children components , that was declared in the template in run time.
  how can I do it?
  For Example:</p>
  
  <pre><code>@Component({
  
  template: `
  &lt;cmp1 *ngIf=expression&gt;&lt;/cmp1&gt;
  &lt;cmp2 *ngIf=!expression&gt;&lt;/cmp2&gt;
      `
  
  })
  export class Component3{
  
  findChild(){
  // How to find cmp2
  }
  
  }
  </code></pre>