Using ionic 4,Trying to give an exit alert message to the user before the app gets closed using hardware back button press event

问题

On my very initial stage.I am trying to give an ‘Exit the App - Yes/No? ‘ alert when the user presses the hardware back button either from the Login Page or from the home page (after login). The problem I am facing is that the Exit alert message appears on every page when I press the back button and not simply on the Login or home page. Moreover automatically navigating backwards regardless if I press ‘No’ option in the alert box. ] Apologies if have done something wrong I this my first post here. The code I using attaching below-

import { Component, OnInit } from '@angular/core';
import{ Router } from '@angular/router';//
import { AlertController } from '@ionic/angular';
import { Subscription } from 'rxjs';

@Component({
  selector: 'app-streams-list',
  templateUrl: './streams-list.page.html',
  styleUrls: ['./streams-list.page.scss'],
})
export class StreamsListPage implements OnInit {

  subscripcion: Subscription;

  constructor(
    public router:Router,
    public alertController: AlertController) {}

  ngOnInit() {

    this.getBackButtonClick();

  }


  getBackButtonClick(){
    this.subscripcion = this.platform.backButton.subscribe(()=>{
        //navigator['app'].exitApp();
        this.ClosingApp();
    });
 }



  async ClosingApp()
 {
      let alert = await this.alertController.create({
      header: 'Confirm',
      message: 'Message to confirm!!!',
      buttons: [{
        text: "OK",
        handler: () => { this.exit() }
      }, {
        text: "Cancel",
        role: 'cancelar',
      }]
    })
     alert.present();
 }

 exit()
 {
  navigator["app"].exitApp();
 }


}

回答1:

You can try this approach based on routing. in app.component.ts

constructor(private router: Router){}

Inside your getBackButtonClick()

 getBackButtonClick(){
  this.subscripcion = this.platform.backButton.subscribe(()=>{
   if (this.route.url == '/login' || this.route.url == '/home'){ //please change if your path name is different for login and home
     this.ClosingApp();
    }
 });
}

Further you need to unsubscribe from this

  ngOnDestroy() {
   this.platform.backButton.unsubscribe();
}

回答2:

You need to unsubscribe from that this.platform.backButton observable in ngOnDestroy lifecycle method like below :

ngOnDestroy() {
    this.subscription.unsubscribe();
}

来源：https://stackoverflow.com/questions/59543013/using-ionic-4-trying-to-give-an-exit-alert-message-to-the-user-before-the-app-ge

标签

angular

ionic-framework