-(NSObject *)func1WithError:(NSError **)error; func func1() throws -> NSObject do { let a: AAA = AAA() let b: NSObject = try a.func1() } catch { print(error) print("--") print(type(of: error)) print("--") dump(error) }nilError -- _GenericObjCError -- - Foundation._GenericObjCError.nilError-(NSObject * _Nullable)func1WithError:(NSError * _Nullable * _Nullable)error; これで全く同じだったよ