On focus ionic input does't slide up with virtual keyboard.

chat.html

<ion-view view-title="{{vm.headetTilte}}" hide-back-button="true" class="purple-back watermark-addComp comment">
  <ion-nav-buttons side="left">
    <button class="button button-icon button-clear ion-android-arrow-back sidebar-ion-navicon" ng-click="vm.goBack()"></button>
  </ion-nav-buttons>
  <ion-content class="padding commentListMarginBottom">
    <ion-list id="commentEmpty" ng-show="vm.Idea.length===0" class="teacher-complaint-list">
      <ion-item id="cmplEmpty">
        <h3>Dummy content</h3>
      </ion-item>
    </ion-list>
  </ion-content>
  <div class="commentForm">
    <form name="commentForm" class="row" ng-submit="vm.addComment(vm.teacher)">
      <div class="row" style="margin-top:-10px !important">
        <div class="col col-90">
          <textarea id="comment-textarea" row="5" ng-model="vm.teacher.comment" placeholder="Type a comment..." required></textarea>
        </div>
        <div class="col commentBtn">
          <button type="submit" id="send" class="button button-icon icon-left ion-android-send"></button>
        </div>
      </div>
    </form>
  </div>
</ion-view>

Styles

.commentForm {
    background-color: $btn-bg-color;
    height: 12%;
    width:100%;
    position: fixed;
    bottom: 0;
    textarea {
        resize: none;
        margin-top: 2px;
        position: absolute;
        width: $width - 20%;
        height: $height - 20%;
        color: $color-white;
        background-color: $transparent;
    }
    .commentBtn {
        top: 50%;
        margin-top:0;
        height: $height;
        position: absolute;
        transform: translateY(-50%);
        button {
            top: 50%;
            position: relative;
            color: $color-white;
            transform: translateY(-50%);
            color: $btn-bg-color;
        }
    }
}

Above is the code of my ionic app. The footer part is sticked to bottom and the form in it doesn't slide up with virtual keyboard. This code is working fine in android devices, problem is only with ios devices only. Please send the solution I am stucked in it since last 2 days.