ionic 3在显示隐藏时设置动画

<ion-content>
  <ion-button (click)="toggleElement()">Toggle Element</ion-button>
  <div [@fadeIn] *ngIf="showElement" class="animated">
    This element will be animated when shown or hidden.
  </div>
</ion-content>

import { Component } from '@angular/core';
import { trigger, state, style, animate, transition } from '@angular/animations';

@Component({
  selector: 'app-home',
  templateUrl: 'home.page.html',
  styleUrls: ['home.page.scss'],
  animations: [
    trigger('fadeIn', [
      state('void', style({ opacity: 0 })),
      state('*', style({ opacity: 1 })),
      transition('void <=> *', animate('300ms')),
    ]),
  ],
})
export class HomePage {
  showElement: boolean = false;

  toggleElement() {
    this.showElement = !this.showElement;
  }
}