ionViewDidEnter method is not fired when pressed back button

discover.html(Ionic page)

 <p>MY TOPICS</p>
      <div class="cardScroll">
        <ng-template ngFor let-topic [ngForOf]="topicdata">
          <topic [data]="topic"></topic>
        </ng-template>
 </div>

discover.ts

@IonicPage()
@Component({
  selector: 'page-discover',
  templateUrl: 'discover.html',
})
export class Discover {

  constructor() {
  }

  ionViewDidEnter() {
    this.GetData();
  }
}

topic.html

   <ion-card (click)="getTopicPage()">

    </ion-card>

topic.ts

import { Component, Input } from '@angular/core';
import { NavController, App } from 'ionic-angular';

@Component({
    selector: 'topic',
    templateUrl: 'topic.html'
})
export class Topic {
    @Input() data;

    constructor(public navCtrl: NavController, public appCtrl: App) {
    }


    getTopicPage() {
        this.appCtrl.getRootNav().push('TopicPage', { data: this.data });
    }

}

topic-page.html

<ion-content>
 <button ion-button clear (click)='goToBack()'><ion-icon name="arrow-back">
 </ion-icon></button>
</ion-content>

topic-page.ts

@IonicPage()
@Component({
    selector: 'page-topic-page',
    templateUrl: 'topic-page.html',
})
export class TopicPage {

    goToBack(): void {
       this.navCtrl.pop();
     }
}

Hope you can see the flow of the components above.The parent page is discover.The problem here is when I pressed the topic-page back button where it never fires the discover page's ionViewDidEnter() method.Can you tell me how to do that?

Note: When I pressed the back button it comes to discover page.But it never fires the ionViewDidEnter() method.