ios - CPTPlotSymbol larger touch area -

how can make plot symbol touch area bigger. 10x10 need filled color, hard touch on screen 'fat' fingers. need area around activate symbol, not filled color.

cptmutablelinestyle *symbollinestyle = [cptmutablelinestyle linestyle];     symbollinestyle.linecolor = [cptcolor colorwithcomponentred:42./255. green:150./255. blue:232./255. alpha:1.]; cptplotsymbol *plotsymbol = [cptplotsymbol ellipseplotsymbol]; plotsymbol.fill               = [cptfill fillwithcolor:[cptcolor colorwithcomponentred:42./255. green:150./255. blue:232./255. alpha:1.]]; plotsymbol.linestyle          = symbollinestyle; plotsymbol.size               = cgsizemake(10.0, 10.0); datasourcelineplot.plotsymbol = plotsymbol; 

in method make plot , graph there should line goes this.

_yourgraph.plotsymbolmarginforhitdetection = 20.0f; 

i use 20.0f because of 'fat' fingers too. have method called configureplots, reference graph , plot space. call plotsymbol... hope helps, ask questions if have any.