There are two methods: the first method is to download the IPA package of the App through iTunes of OS X, and after unpacking, see if there is a framework directory in the App with the Swift runtime, but this method can only judge whether the App uses Swift, but not whether it is mainly written in Swift. The second method, of course, is to share it at some activities and meetings in the industry, that is, the development team will take the initiative to tell the outside world. Lucky Car is a foreign taxi tool similar to Uber, and the latest version has just been written entirely in Swift. "Enjoy ~ Select Limited Food" is the first App written by Swift in China, which comes from Beijing Fanben team. Minimum support for iOS 7. Xiaoji is a vertical writing tool of literary model, which comes from Guangzhou Catch team, and I also started to use it in internal testing. Well, as mentioned above, only iOS 8 is supported.