Capital-Cities

App is created by following Hacking by Swift book by Paul Hudson.

As an challenge exercises I've implemented following features:

• Try typecasting the return value from dequeueReusableAnnotationView() so that it's an MKPinAnnotationView. And change it's pinTintColor property.
• Add a UIAlertController that lets users specify how they want to view the map.
• Modify the callout button so that pressing it shows a new view controller with a web view, taking users to the Wikipedia entry for that city.