Turf for Swift

📱     🖥💻     📺     ⌚️    
           

A spatial analysis library written in Swift for native iOS, macOS, tvOS, watchOS, and Linux applications, ported from Turf.js.

Turf for Swift is experimental and its public API is subject to change. Please use with care and open issues for any problems you see or missing features that should be added.

Requirements

Turf is written in Swift 4. It requires Xcode 9.x and supports the following minimum deployment targets:

• iOS 8.0 and above
• macOS 10.10.0 (Yosemite) and above
• tvOS 9.0 and above
• watchOS 2.0 and above

Alternatively, you can incorporate Turf into a command line tool without Xcode on any platform that Swift supports, including Linux.

If your project is written in Objective-C, you’ll need to write a compatibility layer between turf-swift and your Objective-C code. If your project is written in Objective-C++, you may be able to use spatial-algorithms as an alternative to Turf.

Installation

Although a stable release of this library is not yet available, prereleases are available for installation using any of the popular Swift dependency managers.

CocoaPods

To install Turf using CocoaPods:

1. Specify the following dependency in your Podfile:

   pod 'Turf', '~> 0.3'

2. Run pod repo update if you haven’t lately.
3. Run pod install and open the resulting Xcode workspace.
4. Add import Turf to any Swift file in your application target.

Carthage

To install Turf using Carthage:

1. Add the following dependency to your Cartfile:

   github "mapbox/turf-swift" ~> 0.3
   

2. Run carthage bootstrap.
3. Follow the rest of Carthage’s integration instructions. Your application target’s Embedded Frameworks should include Turf.framework.
4. Add import Turf to any Swift file in your application target.

Swift Package Manager

To install Turf using the Swift Package Manager, add the following package to the dependencies in your Package.swift file:

.Package(url: "https://github.com/mapbox/turf-swift.git", .upToNextMinor(from: "0.2"))

Then import Turf in any Swift file in your module.

Available functionality

This work-in-progress port of Turf.js contains the following functionality:

Turf.js	Turf-swift
turf-along	LineString.coordinateFromStart(distance:)
turf-area	Polygon.area
turf-bezier-spline	LineString.bezier(resolution:sharpness:)
turf-boolean-point-in-polygon	Polygon.contains(point:ignoreBoundary:)
turf-destination	CLLocationCoordinate2D.coordinate(at:facing:) RadianCoordinate2D.coordinate(at:facing:)
turf-distance	CLLocationCoordinate2D.distance(to:) RadianCoordinate2D.distance(to:)
turf-helpers#polygon	Polygon(outerRing:innerRings:)
turf-helpers#lineString	LineString(_:)
turf-helpers#degreesToRadians	CLLocationDegrees.toRadians()
turf-helpers#radiansToDegrees	CLLocationDegrees.toDegrees()
turf-helpers#convertLength turf-helpers#convertArea	Measurement.converted(to:)
turf-length	LineString.distance(from:to:)
turf-line-intersect	Turf.intersection(_:_:)
turf-line-slice	LineString.sliced(from:to:)
turf-line-slice-along	LineString.trimmed(from:distance:)
turf-midpoint	mid(_:_:)
turf-nearest-point-on-line	LineString.closestCoordinate(to:)
—	CLLocationCoordinate2D.direction(to:) RadianCoordinate2D.direction(to:)
—	CLLocationDirection.difference(from:)
—	CLLocationDirection.wrap(min:max:)

GeoJSON

turf-swift also contains an experimental GeoJSON encoder/decoder with support for Codable.

// Decode unknown GeoJSON type
let geojson = try! GeoJSON.parse(data: data)

// Decode known GeoJSON type
let geojson = try! GeoJSON.parse(data: data, as: FeatureCollection.self)

// Initialize a PointFeature and encode as GeoJSON
let coordinate = CLLocationCoordinate2D(latitude: 0, longitude: 1)
let point = Point(coordinate)
let pointFeature = PointFeature(point)
let data = try! JSONEncoder().encode(pointFeature)
let json = String(data: data, encoding: .utf8)
print(json)

/*
{
  "type": "Feature",
  "geometry": {
    "type": "Point",
    "coordinates": [
      1,
      0
    ]
  }
}
*/