Implement IOS UIWebView javascript interface

I need to implement a javascript interface in an existing IOS swift app. Basically I would like to make a call in the javascript that executes a native function in IOS swift and returns a result. The framework I'm using is UIWebView. One of the functions that will be called from javascript will execute an existing function in IOS swift: generate a toast message. Another function will be called from javascript and the swift will return the localization information (country) to the javascript. For this project the deliverables will be a simple, working example xcode project that implements the 2 functions in swift with UIWebView. The other deliverable is an example javascript source file that calls the swift functions. If you're interested in this job please begin your response with the word "Toast".