Added service to show toast message.

src/app/app.module.ts

@@ -15,6 +15,7 @@ import { IonicStorageModule } from '@ionic/storage';
 import { AppComponent } from './app.component';
 import { AppRoutingModule } from './app-routing.module';
 import { RestService } from './rest.service';
+import { ToastService } from './services/toast.service';
 
 @NgModule({
   declarations: [AppComponent],
@@ -31,6 +32,7 @@ import { RestService } from './rest.service';
     StatusBar,
     SplashScreen,
     RestService,
+    ToastService,
     { provide: RouteReuseStrategy, useClass: IonicRouteStrategy }
   ],
   bootstrap: [AppComponent]

src/app/services/toast.service.spec.ts

+import { TestBed } from '@angular/core/testing';
+
+import { ToastService } from './toast.service';
+
+describe('ToastService', () => {
+  beforeEach(() => TestBed.configureTestingModule({}));
+
+  it('should be created', () => {
+    const service: ToastService = TestBed.get(ToastService);
+    expect(service).toBeTruthy();
+  });
+});

src/app/services/toast.service.ts

+import { Injectable } from '@angular/core';
+import { ToastController } from '@ionic/angular';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class ToastService {
+
+  toast: any;
+
+  constructor(public toastController: ToastController) { }
+
+  showToast(message) {
+    this.toast = this.toastController.create({
+      message: message,
+      duration: 2000
+    }).then((toastData)=>{
+      toastData.present();
+    });
+  }
+  HideToast(){
+    this.toast = this.toastController.dismiss();
+  }
+}