ios - Draw with core graphics only inside the circle -

i need implement xy dynamic plot - drawing in realtime. have 2 methods, first of draw circle fill color:

- (void) drawcirclewithfillcolorcomponent:(float)value {     cgpoint center = cgpointmake(self.bounds.size.width / 2, self.bounds.size.height / 2);     cgfloat radius = min(center.x, center.y)-5.f;     uibezierpath *path = [self bezierarcwithcenter:center                                         startangle:0                                           endangle:m_pi*2                                             radius:radius];     [[uicolor whiteappcolor] setstroke];     [[self colorwithvalue:currentvalue] setfill];     [path setlinewidth:1.f];     [path fill];     [path stroke]; }  

and draw graph:

- (void)drawhistoryincontext:(cgcontextref)context bounds:(cgrect)bounds {     cgfloat value;      uibezierpath *graph = [uibezierpath new];      (nsuinteger counter = 0; counter < historyarray.count; counter++) {         value = [historyarray[counter] floatvalue];         if (counter == 0) {             [graph movetopoint:cgpointmake(bounds.origin.x+5+bounds.size.width/2/50, bounds.origin.y+bounds.size.height/2-(value-1)*bounds.size.height/12)];         } else {             [graph addlinetopoint:cgpointmake(bounds.origin.x+5+(float)counter/(float)(50-1)*bounds.size.width/2, max(bounds.origin.y+bounds.size.height/2-(value-1)*bounds.size.height/12,0))];         }     }      [graph setlinewidth:2.f];     [[uicolor lightblueappcolor] setstroke];     [graph stroke]; } 

the problem - background of graph circle. need clip graph inside circle. area drawing graph rectangle - graph line displayed outside of circle borders. how can clip graph?

the unwanted behaviour this:

you can clip context, depending on drawrect: implementation. in essence, clip before drawing graph line, draw. clipping affects drawing happening afterwards, can save context (using cgcontextsavegstate) , restore (using cgcontextrestoregstate) if need draw later not want clipped.