Swift 3 Slippy Map Tiles Counter

swift_slippy_counter.swift

//Swift 3 - Slippy Map Tile Counter

import UIKit
import CoreLocation
private func long2tile(lon: Double, zoom: Int) -> Int {
    let z = Double(zoom)
    return Int(floor((lon+180) / 360 * pow(2.0, z)))
}
private func lat2tile(lat: Double, zoom: Int) -> Int {
    let z = Double(zoom)
    return Int(floor((1 - log(tan(lat * M_PI/180) + 1 / cos(lat * M_PI/180)) / M_PI) / 2 * pow(2, z)));
}

//can't import Mapbox SDK so can't use MGLCoordinateBounds
//private func countTiles(minZoom: Int, maxZoom: Int, bbox: MGLCoordinateBounds) -> Int{
private func countTiles(minZoom: Int, maxZoom: Int) -> Int{
    /**
     * Count Tiles from BBOX (Swift 3)
     * Original Python Version https://gist.github.com/ThomasG77/1677408
     *
     **/
    
    //uncomment
    //let latmin = bbox.sw.latitude
    //let latmax = bbox.ne.latitude
    //let lonmin = bbox.sw.longitude
    //let lonmax = bbox.ne.longitude
    
    //remove, hardcoded for testing
    let latmin = CLLocationDegrees(exactly: 12.96524048)!
    let latmax = CLLocationDegrees(exactly: 13.06549072)!
    let lonmin = CLLocationDegrees(exactly: 47.77163739)!
    let lonmax = CLLocationDegrees(exactly: 47.81684332)!
    
    var tileCount: Int = 0;
    for z in minZoom...maxZoom {
        let txmin = long2tile(lon: lonmin, zoom: z);
        let txmax = long2tile(lon: lonmax, zoom: z);
        let tymin = lat2tile(lat: latmax, zoom: z);
        let tymax = lat2tile(lat: latmin, zoom: z);
        for _ in txmin...txmax {
            for _ in tymin...tymax {
                tileCount += 1;
            }
        }
    }
    return tileCount;
}

let count = countTiles(minZoom: 12, maxZoom: 18)
print("# of tiles", count)