title: Get selected value of ion-radio-group tag in ionic 4
body: <p>I have a code in below :</p>
  
  <pre><code>&lt;ion-item&gt;
   &lt;ion-radio-group [value]="profileItem.Sex" [(ngModel)]="profileItem.Sex"&gt;
    &lt;ion-label class="input-label"&gt;{{ 'GENDER' | translate }}&lt;/ion-label&gt;
    &lt;div style="display: flex;"&gt;
      &lt;span *ngFor="let genderType of genderTypeList"&gt;
        &lt;span&gt;{{genderType.title}}&lt;/span&gt;
        &lt;ion-radio [disabled]="profileItem.id" [value]="genderType.value"&gt;&lt;/ion-radio&gt;
      &lt;/span&gt;
    &lt;/div&gt;
   &lt;/ion-radio-group&gt;
  &lt;/ion-item&gt;
  </code></pre>
  
  <p>but can not get selected value in profileItem.Sex.<br>
  profileItem.Sex not changed.<br>
  how to get selected value in ion-radio-group tag ?</p>