例如我们有简单的枚举publicenumCXActionSheetToolBarButtonItem{casecancelcasedonecasenowprivatestaticvartitles:[CXActionSheetToolBarButtonItem:String]=[.cancel:"Cancel",.done:"Done",.now:"Now",]publicvartitle:String{get{returnCXActionSheetToolBarButtonItem.titles[self]??String(describing:self)}//whatamIwant