SearchController with MapKit

I practice SearchController and display search result follow this article:

https://www.thorntech.com/2016/01/how-to-search-for-location-using-apples-mapkit/

and I update the code to Swift 3.0

1. Clear background toolbar.
2. A beautiful MKUserTrackingBarButtonItem.
3. Custom UINavigationBar style.
4. remove some code I don't need.

1. UISearchResultUpdating
2. MapKit
3. UISearchController
4. MKLocalSearchRequest