Cetacea is a markdown written for iOS & macOS. When building Cetacea, I managed to maintain both iOS and macOS versions in a workspace, with most reusable codes in a framework called "CetaceaSharedFramework". You can see that Cetacea was running on iOS simulator and macOS at the same time in the image below.
Cetacea was abandoned due to technical difficulties mainly. Also, I didn't have enough time to pull it off as later I went to Baidu for an internship.