I have a comment, not related to your question, but that I believe is a valid point to improve your game. Stay away from an absolute joystick for this platform game of yours, Touch screens have no tactile feedback, so it's very easy for the player to "lose" the arrows positions.
A touch relative joystick, that is, a joystick that anchors itself where the player touches, might be a better choice. It's easy to implement and your players will have a far better experience.
If you have any problem implementing such a controller, just PM me or tag me in a thread and I could walk you through.
I'm trying to make a touch joystick so that where ever it points the player points. Please tell me how to make said joystick.