覆盖ionic 4中的工具栏后退按钮操作

const routes: Routes = [
  { path: '', redirectTo: '/home', pathMatch: 'full' },
  { path: 'home', component: HomePage },
  { path: 'about', component: AboutPage }
];

import { NavController } from '@ionic/angular';

constructor(private navCtrl: NavController) {}

ionViewDidEnter() {
  // 监听后退按钮事件
  window.addEventListener('ionBackButton', (ev) => {
    ev.detail.register(-1, () => {
      // 自定义后退逻辑
      console.log('Custom back button action');
      // 例如，弹出确认对话框
      this.presentConfirmExit();
    });
  });
}

async presentConfirmExit() {
  const alert = await alertController.create({
    header: '退出',
    message: '确定要退出应用吗？',
    buttons: [
      {
        text: '取消',
        role: 'cancel'
      },
      {
        text: '确定',
        handler: () => {
          navigator['app'].exitApp();
        }
      }
    ]
  });

  return await alert.present();
}

<ion-toolbar>
  <ion-buttons slot="start">
    <ion-back-button defaultHref="/home" (ionBackButton)="customBackAction()"></ion-back-button>
  </ion-buttons>
  <ion-title>页面标题</ion-title>
</ion-toolbar>

customBackAction() {
  // 自定义后退逻辑
}