SwiftGeographic

Accurate geodetic coordinate conversions between geographic (latitude/longitude), UTM, UPS, and MGRS coordinate systems for Swift.

Features

• High-precision projections: Transverse Mercator via Karney's 6th-order Krueger series (sub-nanometer accuracy) and Polar Stereographic via Snyder's formulation
• Full coordinate system support: Convert between geographic, UTM, UPS, and MGRS coordinates on the WGS84 ellipsoid
• MGRS at any precision: 12 precision levels from 100 km down to 1 micrometer
• Zone exceptions handled: Norway (zone 32V) and Svalbard (31X/33X/35X/37X) exceptions are applied automatically
• Polar coverage: UPS seamlessly covers latitudes above 84N and below 80S
• Swift 6 concurrency: All types are Sendable
• Type safety: Strongly typed coordinate structs with validation on creation
• No dependencies: Pure Swift implementation with zero external dependencies

Requirements

• Swift 6.0+
• macOS 13+, iOS 16+, tvOS 16+, watchOS 9+, or visionOS 1+

Installation

Swift Package Manager

Add SwiftGeographic to your Package.swift:

dependencies: [
    .package(url: "https://github.com/riscfuture/SwiftGeographic.git", from: "1.0.0")
]

Then add the dependency to your target:

.target(
    name: "YourTarget",
    dependencies: ["SwiftGeographic"]
)

Or in Xcode: File > Add Package Dependencies > Enter the repository URL.

Quick Start

Geographic to UTM

import SwiftGeographic

let coord = try GeographicCoordinate(latitude: 40.7128, longitude: -74.0060)
let utm = try coord.utm

print(utm.zone)       // 18
print(utm.hemisphere)  // .north
print(utm.easting)     // ~583960
print(utm.northing)    // ~4507523

Geographic to MGRS

let mgrs = try coord.mgrs()                         // 1-meter precision
let mgrs10m = try coord.mgrs(precision: .tenMeter)  // 10-meter precision

Parsing MGRS

let parsed = try MGRSCoordinate(string: "18TXL8396007523")
let geo = try parsed.geographic
print(geo.latitude)   // ~40.7128
print(geo.longitude)  // ~-74.0060

Polar Regions (UPS)

let pole = try GeographicCoordinate(latitude: 89.0, longitude: 0.0)
let ups = try pole.ups
let mgrs = try pole.mgrs()

Round-Tripping

let original = try GeographicCoordinate(latitude: 48.8566, longitude: 2.3522)
let utm = try original.utm
let restored = try utm.geographic
// restored is within nanometers of original

Running Tests

swift test

Building Documentation

Generate documentation locally with:

swift package generate-documentation --target SwiftGeographic

Preview it in a browser:

swift package --disable-sandbox preview-documentation --target SwiftGeographic

Documentation

Full documentation is available at riscfuture.github.io/SwiftGeographic.

License

SwiftGeographic is released under the MIT License. See LICENSE.md for details.