ios - How to optimize CPU and RAM usage on a UIView which uses `drawInRect:blendMode:`? -

i'm developing drawing app lets user draw 1 uibezierpath once on image has been drawn in uiview drawinrect:blendmode in drawrect method , it's uses on 80% of cpu , 55mb of ram , when traced down in time profiler, drawinrect:blendmode method causing of cpu usage. have done few optimizations further optimizations can both drawing uiimage being drawn using [image drawinrect:rect]; , uibezierpath user draws on top of it? in advance.

@interface insideview(){     cgrect imagerect;     cgrect targetbounds; } @property (strong, nonatomic) nsmutablearray *strokes; @property (nonatomic, strong) uiimage * img; @property (nonatomic, strong) uibezierpath *drawingpath; @end  @implementation insideview  -(void)drawrect:(cgrect)rect{     targetbounds = self.layer.bounds;     imagerect = avmakerectwithaspectratioinsiderect(self.img.size,targetbounds);     [self.img drawinrect:imagerect];      (int i=0; < [self.strokes count]; i++) {          uibezierpath* tmp = (uibezierpath*)[self.strokes  objectatindex:i];          [[uicolor whitecolor] setstroke];          [tmp stroke];     } } - (cgrect)segmentboundsfrom:(cgpoint)point1 to:(cgpoint)point2 {     cgrect dirtypoint1 = cgrectmake(point1.x-10, point1.y-10, 50, 50);     cgrect dirtypoint2 = cgrectmake(point2.x-10, point2.y-10, 50, 50);     return cgrectunion(dirtypoint1, dirtypoint2); } - (void)touchesbegan:(nsset *)touches withevent:(uievent *)event{      self.drawingpath = [uibezierpath bezierpath];     self.drawingpath.linewidth = 10;     self.drawingpath.linecapstyle = kcglinecapround;     self.drawingpath.linejoinstyle = kcglinejoinround;     [self.drawingpath movetopoint:[[touches anyobject] locationinview:self]];     [self.strokes addobject:self.drawingpath]; } - (void)touchesmoved:(nsset *)touches withevent:(uievent *)event{     //dirty rect calculations     cgpoint prevpoint = cgpathgetcurrentpoint(self.drawingpath.cgpath);     cgpoint point = [[touches anyobject] locationinview:self];     cgrect dirty = [self segmentboundsfrom:prevpoint to:point];      [[self.strokes lastobject] addlinetopoint:point];     [self setneedsdisplayinrect:dirty]; } - (void)touchesended:(nsset *)touches withevent:(uievent *)event{     [[self.strokes lastobject] addlinetopoint:[[touches anyobject] locationinview:self]];     [self setneedsdisplay]; }