iphone - Draw part of a circle -

for iphone application want draw circle, x percentage filled.

something this:

i have no problems calculating radius, degrees or radians, no problem. drawing circle done. how iphone sdk draw part filled.

i can draw rectangle size, not part of circle.

i want draw on a normal context.

hope can give me pointers here.

use cgcontext's arc functions:

cgcontextaddarc(context,                 centerx,                 centery,                 radius,                 startangleradians,                 endangleradians,                 clockwise ? 1 : 0);      

see documentation cgcontextaddarc().