Ionic is an open-source development framework for building mobile apps. Ionic Apps are written using HTML, Javascript, and CSS. Ionic support faster developments in comparison to traditional applications and offers better UI interactions with a rich interface.
IOS
Xamarin extends the .NET platform(with other Microsoft tools & libraries) to provide us with 100% native mobile applications. Common code can be written in C# to create applications for Android, IOS as well as UWP.
Nowadays, rapid development is necessary for mobile app development. To achieve this, Xamarin. Forms have introduced Xamarin Shell in the latest version 4.0.