ionic - ion-nav-view not working

I am building a ionic pacakage, having multiple views. I use the route provider to navigate between different views.

app.js

.config(function($routeProvider,$locationProvider){

    $routeProvider
    .when('/search',
        {
            controller : 'MyController',
            templateUrl : 'partials/search.html'
        })

    .when('/not-found/:className',
        {
            controller : 'MyController',
            templateUrl : 'partials/not-found.html'
        })

My index.html 

  <body ng-app="MyApp">  
        <ng-view></ng-view>

      </body>
    </html>

The problem is that the back button on my phone does not work.i.e it does not remember the history. e.g If I go from search.html to not-found.html, when I press the back button on my phone, I expect it to come back to search.html instead it closes my app. I looked and ionic forum and the suggest way to make back button work is to use ion-nav-view. If I replace ng-view with ion-nav-view, the search/not-found page are not rendering, I even tried adding the ion-view on the search/not-found html page.
1) Could you please suggest a way to get my back button working?

In order to achieve that, you actually need to capture the hardware back button pressed event and perform the navigation accordingly or You can use ion-nav-back-button..

  1. Capture the hardware back button event : 

    $ionicPlatform.registerBackButtonAction(function () {
  if (condition) {
    navigator.app.exitApp();
  } else {
    // handle back action!
  }
}, 100);

More Details can be found here

  1. Using ion-nav-back-button

    <ion-nav-bar>
  <ion-nav-back-button class="button-clear">
    <i class="ion-arrow-left-c"></i> Back
  </ion-nav-back-button>
</ion-nav-bar>

More Details about this can be found here