Swift implementation of the geodesic routines in GeographicLib

import PackageDescription

let package = Package(
    name: "MyPackage",

   /* ... */

    dependencies: [
        .package(url: "https://github.com/scottrhoyt/geographiclib-swift.git", from: "0.1.0"),
    ],

   /* ... */

    targets: [
        .target(
            name: "MyPackage",
            dependencies: [
                .product(name: "GeographicLib", package: "geographiclib-swift")
            ]
        )
    ]

   /* ... */

)

import GeographicLib

// Create a geodesic calculator with WGS-84 ellipsoid (default)
let geodesic = Geodesic()

// Solve the direct problem: given a starting point, azimuth, and distance
let direct = geodesic.direct(
    latitude: 40.64,      // JFK Airport
    longitude: -73.78,
    azimuth: 45.0,        // northeast
    distance: 10_000_000  // 10,000 km
)
print("Destination: \(direct.latitude)°, \(direct.longitude)°")

// Solve the inverse problem: given two points, find distance and azimuths
let inverse = geodesic.inverse(
    startLatitude: 40.64,     // JFK Airport
    startLongitude: -73.78,
    endLatitude: 1.36,      // Singapore Changi Airport
    endLongitude: 103.99
)
print("Distance: \(inverse.distance) meters")
print("Initial azimuth: \(inverse.startAzimuth)°")

// Use GRS-80 ellipsoid
let grs80 = Geodesic(.grs80)

// Use a custom ellipsoid
let customEllipsoid = Ellipsoid(equatorialRadius: 6378000.0, flattening: 1.0/300.0)
let customGeodesic = Geodesic(customEllipsoid)

// Use a sphere for simplified calculations
let sphere = Geodesic(.sphere)

// Create a geodesic line
let line = geodesic.inverseLine(
    latitude1: 40.64, longitude1: -73.78,  // JFK
    latitude2: 1.36, longitude2: 103.99     // Singapore
)

// Calculate waypoints
for i in 0...10 {
    let fraction = Double(i) / 10.0
    let position = line.position(distance: line.distance * fraction)
    print("Waypoint \(i): \(position.latitude)°, \(position.longitude)°")
}

// Simple polygon area calculation
let antarctica = [
    (-72.9, -74), (-71.9, -102), (-74.9, -102), (-74.3, -131),
    (-77.5, -163), (-77.4, 163), (-71.7, 172), (-65.9, 140),
    (-65.7, 113), (-66.6, 88), (-66.9, 59), (-69.8, 25),
    (-70.0, -4), (-71.0, -14), (-77.3, -33), (-77.9, -46), (-74.7, -61)
]

let (area, perimeter) = geodesic.polygonArea(coordinates: antarctica)

print("Antarctica area: \(area) m²")
print("Antarctica perimeter: \(perimeter) m")

// Using the Polygon type for more control
var polygon = Polygon()
polygon.addPoint(latitude: 0, longitude: 0)
polygon.addPoint(latitude: 0, longitude: 90)
polygon.addPoint(latitude: 90, longitude: 0)

let result = polygon.compute()
print("Triangle area: \(result.area!) m²")