ios - Fill MKOverlay with specific color and blending mode -

i need fill mkoverlay specific color , kcgblendmodemultiply blending mode. i've implemented mkoverlayrenderer subclass follows:

@interface mapdimoverlayrenderer : mkoverlayrenderer  @property (nonatomic, strong) uicolor *overlaycolor; @property (nonatomic, strong) cgfloat overlayalpha;  @end  @implementation mapdimoverlayrenderer  - (instancetype)initwithoverlay:(id<mkoverlay>)overlay {     self = [super initwithoverlay:overlay];     if (self) {         self.overlayalpha = 0.9;         self.overlaycolor = [uicolor hx_colorwithhexstring:@"2c3239" alpha:self.overlayalpha];     }     return self; }  - (void)drawmaprect:(mkmaprect)maprect zoomscale:(mkzoomscale)zoomscale incontext:(cgcontextref)context {     cgcontextsetblendmode(context, kcgblendmodemultiply);     cgcontextsetfillcolorwithcolor(context, self.overlaycolor.cgcolor);     cgcontextfillrect(context, [self rectformaprect:mkmaprectworld]); }  @end 

the problem cgcontextsetblendmode doesn't affect result. tried set different modes. result same default (kcgblendmodenormal).