I have a similar question, and I figured that it was close enough along the lines of this that making a new thread would be unnecessary.
I originally tried using Unity's animation to animate the alpha of the color property of a sprite. This didn't work.
However, when I change the color value in script, doing something along the lines of this, it works:
Note: direction changes from -1 to 1, depending if color is 1 or 0, and this is run in Update()
Color deltaColor = textLoading.color;
deltaColor.a += direction * Time.deltaTime;
textLoading.color = deltaColor;
Can someone explains why I cannot animation the alpha in a Unity Animation?