Nativescript block Back Button on Android

 Example of blocking Soft Back Button on android in angular component

import { Component, OnInit } from '@angular/core';
import { isAndroid } from '@nativescript/core/platform';
import { AndroidApplication, AndroidActivityBackPressedEventData } from "@nativescript/core/application";
import * as app from "@nativescript/core/application";

declare const android:any;

//Put this code in implementation OnInit of component

ngOnInit() {   
     if (isAndroid) {
      app.android.on(AndroidApplication.activityBackPressedEvent, (data: AndroidActivityBackPressedEventData) => {                      
          data.cancel = true; // prevents default back button behavior          
      });
    }
  }