Birthday gift..?

I want to make a simple app for ios and windows. With data transfer between them later on. I want to make it for a friend. I know ios will be a bit more complicated due to it's closed off system, but I first want to try the windows application. I want to give it more functions later, but for now I just want it to tell the moon's current shade. I also want to draw what it needs to be drawn. If this makes sense.