title: Passing style resource id from XML to class not working
body: <p>I have a custom widget in a library project (Spinnerbutton) that I want to use in an application project. 
  The custom widget contains a TextView and I want to pass a style to that TextView from my app project. </p>
  
  <p>This is my attrs.xml (in the library project): </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;resources&gt;
  
      &lt;declare-styleable name="Spinnerbutton"&gt;
          &lt;attr name="myTextAppearence" format="reference" /&gt;
      &lt;/declare-styleable&gt;
  
  &lt;/resources&gt;
  </code></pre>
  
  <p>And the app's layout: </p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      xmlns:custom="http://schemas.android.com/apk/lib/com.example.spinnerbuttonlib"
      android:id="@+id/root"
      android:layout_width="match_parent"
      android:layout_height="match_parent" &gt;
  
      &lt;com.example.spinnerbuttonlib.spinnerbutton.Spinnerbutton
          android:id="@+id/sbp"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_marginTop="8dp"
          custom:myTextAppearence="@style/SmallTextGray" /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>Here's how I try to read my custom attribute in the Spinnerbutton class: </p>
  
  <pre><code>public Spinnerbutton(Context context, AttributeSet attrs) {
      super(context, attrs);
      this.context = context;
  
      TypedArray a = context.obtainStyledAttributes(attrs,
              R.styleable.Spinnerbutton);
  
      int textStyleId = a.getResourceId(
              R.styleable.Spinnerbutton_myTextAppearence, -1);
  
      a.recycle();
  
  }
  </code></pre>
  
  <p>textStyleId always return -1, so the value is not passed from my layout to the class. </p>
  
  <p>What's wrong here?</p>