How to access parent navController ionic 2
<p>I'm learning Ionic 2 by building a simple app, but I've ran into a problem I can't solve.</p>

<p>The app has a ion-nav for the login page, after logging in it goes into a tabs navigator. So the app nav would be something like:</p>

<pre><code>app&lt;Nav&gt; {
    LoginPage,
    restrictedTabs&lt;Nav&gt; {
        Page1,
        ...
    }
}
</code></pre>

<p>My problem is I don't know how to access appNav while I'm inside Page1, so that I can, for example, logout the user and block him from "restrictedTabs".</p>

<p>I've tried as the docs say with @ViewChild</p>

<pre class="lang-js prettyprint-override"><code>import {Component, ViewChild} from '@angular/core';
import {NavController} from 'ionic-angular';

@Component({
  templateUrl: 'page1url...'
})
export class ProfilePage {
    @ViewChild('appNav') appNav : NavController

    constructor(private _nav: NavController) {

    }

    pushNewPlace() {
        console.log(this._nav.rootNav);
        console.log(this._nav.parent);
    }

    ngAfterViewInit() {
      console.log(this.appNav);
    }
}
</code></pre>

<p>But appNav is always undefined, as is rootNav (which I've seen in some tutorial...). If I try @ViewChild('appNav') on LoginPage controller it works good</p>