Fix iOS build
Fix iOS build

TARGET_OS_MAC will be true for both OS X and iOS, so use TARGET_OS_IPHONE instead.

gauravds/UICKeyChainStore,Kingside/UICKeyChainStore,hulu001/UICKeyChainStore,bigrpg/UICKeyChainStore,dleehr/UICKeyChainStore,royalwang/UICKeyChainStore,HSFGitHub/UICKeyChainStore,dezinezync/UICKeyChainStore,hanhailong/UICKeyChainStore,v2dev/UICKeyChainStore,kishikawakatsumi/UICKeyChainStore,TomoakiNagahara/UICKeyChainStore,imjerrybao/UICKeyChainStore,Ninikitos/UICKeyChainStore,kishikawakatsumi/UICKeyChainStore