iOS iPhone finger paint-like app, is there a built-in canvas or open source projects to help me get started?

Question

I need to implement on-screen drawing feature within one of my apps. I would imagine it would be an on-screen transparent overlay. I'm looking to be able to trace the finger path and leave a line, select colors and have erase/undo feature. I did some research of what's currently on the app store, and a lot of those apps look similar and use similar brushes.

Something tells me that they look too much alike for this to be a coincidence. Does apple provide any built-in finger painting canvas, or are there some widely-known open source projects for on-screen drawing?

Thank you!

Answer 1

There is the GLPaint project, which you can get here.

Other than that, you could use CoreGraphics & -touchesBegan:withEvent: if you wanted.

Answer 2

I ran into the same thing while looking for examples when I got started with drawing, so I released my efforts as a sample project called SimpleDrawing. I tried to keep things basic while supporting most/all of the standard drawing tools and operations.