<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="600"
    android:propertyName="fillAlpha"
    android:valueFrom="0"
    android:valueTo="1"
    android:startOffset="800"
    android:repeatMode="reverse"
    android:repeatCount="infinite"
    android:interpolator="@android:anim/linear_interpolator" />