I have a quilting app on mine. And it was a FREE app. Called Block Fab HD. Has something like 70 blocks in the library. I can tell it how many blocks I want to make and what size and it tells me how much fabric I need and the cutting directions for all colors.
You can set the usuable width, the shrinkage % to help figure yardage.
I can combine blocks onto a quilt of many different size, pair blocks - and look at them in I think 5 different colorways. Can also add plain blocks and sashing.
To figure yardage and cutting for a whole quilt though you have to count the blocks in the quilt then figure the yardage for that block. So if you paired or combined blocks you need to figure out each separately (as well as sashing). It won't calculate the whole quilt.
It's neat, I like it. So far I've played with it but haven't used it to create a quilt. Not because it won't do it, I've just got other projects going on. But it's a neat tool and small and easy enough to bring to the LQS to figure out how much fabric to buy.
Personally, I wouldn't buy an Ipad just for this app. It was just another neat one I added to it. I use my Ipad for a million other things.