How to add ionic project in to existing iOS Native project

I have a Native iOS mobile project, I’m trying to add a new feature by implementing it in Ionic 3, is there any way to port the ionic project in to existing native project? or using a web view ?

Depends on what features you need.

Ionic projects are built with Cordova that provides the native part around the Ionic web app. It also provides some APIs that Ionic uses to interact with the native parts for Cordova plugins etc. So if you just load Ionic’s index.html in a webview all of this will be missing. You can also include the “Cordova Webview” into a native app, but you will have to read the Cordova docs for that.