<?xml version="1.0" encoding="utf-8"?>
<set >
    <alpha
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:fromAlpha="0.0"
        android:toAlpha="1.0"
        android:duration="1000"
        android:repeatMode="reverse"
        android:repeatCount="infinite" />
</set>