Other class view cannot be loaded into TabBar Controller
<p><strong>Hi,</strong></p>

<p>I am making a project with 3 child views that are switched by a TabBar.</p>

<p><strong>What I did</strong></p>

<ol>
<li>Create a project (Window-Based)</li>
<li>Add 3 child classes (Window-Based too)</li>
<li>Add a Tab Bar Controller to MainWindow.xib</li>
<li>For each view under Tab Bar Controller, the 'Class', 'Name', 'Title' and 'NIB Name' are all set to connect to the corresponding class</li>
<li>Add @class, IBOutlet are done in AppDelegate.h and AppDelegate.m</li>
<li>In didFinishLaunchingWithOptions, I called [window addSubView: tabBarController.view];</li>
<li>Save and Run --> Tab Bar with 3 items can be seen</li>
<li>But ... the 3 child views ARE NOT LOADED and SHOWN ... :(</li>
</ol>

<p>Anything that I missed ?</p>

<p>Million Thanks</p>
