I converted the Objective C code from this tutorial
https://www.mapbox.com/guides/station-finder-part-1/
to Swift using a bridge header. Currently, the comments reflect where I feel I deviated from the Objective C version. I would add more tutorial friendly comments later. I wrote in such a way that the code snippets could be added side by side to the Objective C code in the tutorial without too much pain.
I did deviate from the tutorial by adding the "Filter" button to the Nav bar in interface builder only since the Navigation controller was in interface builder.