fixed xcode compiler warning
fixed xcode compiler warning

pflnh/PulsingHalo,niuxinghua/PulsingHalo,mjasa/PulsingHalo,tangwei6423471/PulsingHalo,mitchellporter/PulsingHalo,shu223/PulsingHalo,zxl20zxl/PulsingHalo,Kevin775263419/PulsingHalo,liuruxian/PulsingHalo,fullstackclub/PulsingHalo,AlexanderMazaletskiy/PulsingHalo,brasbug/PulsingHalo