iOS: fix touch build error
iOS: fix touch build error

br111an/oxyplot,Mitch-Connor/oxyplot,sevoku/oxyplot,DotNetDoctor/oxyplot,bbqchickenrobot/oxyplot,jeremyiverson/oxyplot,freudenthal/oxyplot,TheAlmightyBob/oxyplot,shoelzer/oxyplot,svendu/oxyplot,ze-pequeno/oxyplot,olegtarasov/oxyplot,Sbosanquet/oxyplot,DotNetDoctor/oxyplot,TheAlmightyBob/oxyplot,Rustemt/oxyplot,objorke/oxyplot,Jofta/oxyplot,H2ONaCl/oxyplot,HermanEldering/oxyplot,lynxkor/oxyplot,olegtarasov/oxyplot,Rustemt/oxyplot,jeremyiverson/oxyplot,br111an/oxyplot,shoelzer/oxyplot,HermanEldering/oxyplot,br111an/oxyplot,lynxkor/oxyplot,as-zhuravlev/oxyplot_wpf_fork,zur003/oxyplot,as-zhuravlev/oxyplot_wpf_fork,objorke/oxyplot,GeertvanHorrik/oxyplot,Kaplas80/oxyplot,GeertvanHorrik/oxyplot,mattleibow/oxyplot,bbqchickenrobot/oxyplot,Mitch-Connor/oxyplot,bbqchickenrobot/oxyplot,BRER-TECH/oxyplot,Sbosanquet/oxyplot,lynxkor/oxyplot,shoelzer/oxyplot,Jonarw/oxyplot,jeremyiverson/oxyplot,GeertvanHorrik/oxyplot,sevoku/oxyplot,NilesDavis/oxyplot,freudenthal/oxyplot,H2ONaCl/oxyplot,H2ONaCl/oxyplot,objorke/oxyplot,mattleibow/oxyplot,Rustemt/oxyplot,Sbosanquet/oxyplot,oxyplot/oxyplot,svendu/oxyplot,as-zhuravlev/oxyplot_wpf_fork,Kaplas80/oxyplot,svendu/oxyplot,TheAlmightyBob/oxyplot,Isolocis/oxyplot,freudenthal/oxyplot,BRER-TECH/oxyplot,Mitch-Connor/oxyplot