如何在ionic 3中创建折叠工具栏

ionic start myApp blank --type=angular

cd myApp

<ion-header>
  <ion-toolbar>
    <ion-buttons slot="start">
      <ion-menu-button></ion-menu-button>
    </ion-buttons>
    <ion-title>
      My App
    </ion-title>
  </ion-toolbar>
  <ion-toolbar>
    <ion-segment [(ngModel)]="segment">
      <ion-segment-button value="segment1">
        Segment 1
      </ion-segment-button>
      <ion-segment-button value="segment2">
        Segment 2
      </ion-segment-button>
    </ion-segment>
  </ion-toolbar>
</ion-header>

<ion-content>
  <div [ngSwitch]="segment">
    <div *ngSwitchCase="'segment1'">
      Content for Segment 1
    </div>
    <div *ngSwitchCase="'segment2'">
      Content for Segment 2
    </div>
  </div>
</ion-content>

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html',
  styleUrls: ['app.component.scss'],
})
export class AppComponent {
  segment: string = 'segment1';
}

ionic serve