Question

I am working on a drawing app, with pen touch, on iphone and ipad. Till now , I have implemented the basic drawing and tested with digital pen and it work fine, but I have one issue, while drawing on iphone/ipad, if my fingers touch the screen before I draw with pen , the pen wont work, So what I want to achieve is that, I want to able to write with pen, even if my fingers are touching the ipad screen.

Regards
Ranjit

Answer 1

There is no way to differentiate between a finger and a stylus, as a stylus is supposed to emulate a touch from a finger. You will either have to make it so that all touches draw (including a hand on the screen) or make it so only the first “finger” that touches the screen can draw (meaning that you must put the stylus on the screen before your hands can touch it).

@iLive is correct in mentioning those delegate methods that you should implement, but I assume that you are already using these methods.

UPDATE:

Tracking specific touches is as simple as adding the addresses of their instances to a array during touchesBegan. Append them to a CFMutableArrayRef. Then, in the touchesMoved method, you can simply get the index of the touch in order.