title: angular 2 NgFor only supports binding to Iterables such as Arrays
body: <p>i am using Reactive form pattern in angular 2 project. I would like to populate a container dynamically with answers(answers object is fetched and populated using http call).</p>
  
  <p>Reactive form object structure:</p>
  
  <pre><code>public questionDetailForm = this.fb.group({
      type    : ['', Validators.required],
      title   : ['', Validators.required],
      required: [false],
      answers : this.fb.array([])
  });
  </code></pre>
  
  <p>helper array to populate 'answers' key of 'questionDetailForm' object:</p>
  
  <pre><code>public formArray = &lt;FormArray&gt;this.questionDetailForm.controls['answers'];
  </code></pre>
  
  <p>'formArray' is populated by http call response data:</p>
  
  <pre><code>if (response.data.question.answers != null &amp;&amp; response.data.question.type_id !== 400 &amp;&amp; response.data.question.type_id !== 800) {
      for (const key in response.data.question.answers) {
          if (response.data.question.answers.hasOwnProperty(key)) {
             this.formArray.push(new FormControl(response.data.question.answers[key] , Validators.required));
          }
      }
  }
  </code></pre>
  
  <p>the problem arises in html file(highlighted in bold):</p>
  
  <pre><code>&lt;div fxLayout="row" fxFlexOffset="10" *ngFor="let answer of **questionDetailForm.controls['answers'];** let i = index" class="base-input-container answer-container"&gt;
      &lt;md-input-container fxFlex="70" [ngClass]="{haserror: formErrors.answer &amp;&amp; i === answerIndexError}"&gt;
         &lt;input mdInput type="text" [formControl]="answer" placeholder="Answer"&gt;
      &lt;/md-input-container&gt;
      &lt;button type="button" fxFlexOffset="3" class="remove-answer" md-fab mdTooltip="remove answer" (click)="removeAnswer(i)" color="primary"&gt;&lt;i class="material-icons"&gt;remove&lt;/i&gt;&lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I have just updated from angular-cli beta version to 1.0.0. I have not faced the same issue using the beta version.</p>