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Projections

Last updated: March 31, 2026 | 4 minutes read

Learn how to create projection objects and convert between coordinate systems using ProjectionContext.

Supported projection types​

  • WGS84 - World Geodetic System 1984
  • GK - Gauss-Kruger
  • UTM - Universal Transverse Mercator
  • LAM - Lambert
  • BNG - British National Grid
  • MGRS - Military Grid Reference System
  • W3W - What three words

WGS84 projection​

The WGS84 projection is a widely used geodetic datum that serves as the foundation for GPS and other mapping systems.

Create a WGS84 projection using coordinates:

let wgs = ProjectionWGS84Object(
    coordinates: CoordinatesObject.coordinates(withLatitude: 51.5074, longitude: -0.1278)
)

Access and modify coordinates using the getter and setter:

if let coords = wgs.getCoordinates() {
    print("latitude=\(coords.getLatitude()) longitude=\(coords.getLongitude())")
}

wgs.setCoordinates(
    CoordinatesObject.coordinates(withLatitude: 10.0, longitude: 10.0)
)

GK projection​

The Gauss-Kruger projection is a cylindrical map projection commonly used for large-scale mapping in regions with a north-south orientation. It divides the Earth into zones, each with its own coordinate system.

Create a Gauss-Kruger projection:

let gk = ProjectionGKObject(x: 6325113.72, y: 5082540.66, zone: 1)

Access and modify values using getter and setter methods:

let easting = gk.getEasting()
let northing = gk.getNorthing()
let zone = gk.getZone()

print("easting=\(easting) northing=\(northing) zone=\(zone)")

gk.setX(1, setY: 1, zone: 2)
danger

The Gauss-Kruger projection is currently supported only for countries that use the Bessel ellipsoid. Converting to and from Gauss-Kruger projection for other countries will result in an SDKErrorCode error.

BNG projection​

The BNG (British National Grid) projection is a coordinate system used in Great Britain for mapping and navigation. It provides a grid reference system for precise location identification.

Create a BNG projection using easting and northing:

let bng = ProjectionBNGObject(easting: 500000, northing: 4649776)

Or create from a grid reference string:

let bng2 = ProjectionBNGObject(gridReference: "TL56")

Access and modify values:

let easting = bng.getEasting()
let northing = bng.getNorthing()
let gridRef = bng.getGridReference()

print("easting=\(easting) northing=\(northing) grid=\(gridRef)")

bng.setEasting(1, northing: 1)
bng.setGridReference("SJ23")

MGRS projection​

The MGRS (Military Grid Reference System) projection is a coordinate system used by the military for precise location identification. It combines the UTM and UPS coordinate systems.

Create a MGRS projection:

let mgrs = ProjectionMGRSObject(easting: 99316, northing: 10163, zone: "30U", letters: "XC")

Access and modify values:

let easting = mgrs.getEasting()
let northing = mgrs.getNorthing()
let zone = mgrs.getZone()
let sq100k = mgrs.getSq100kIdentifier()

print("easting=\(easting) northing=\(northing) zone=\(zone) sq100k=\(sq100k)")

mgrs.setEasting(1, northing: 1, zone: "B", letters: "AB")

W3W projection​

The W3W (What three words) projection is a geocoding system that divides the world into a grid of 3m x 3m squares, each identified by a unique combination of three words.

Create a W3W projection with an API token:

let w3w = ProjectionW3WObject(token: "your-api-token")

Access and modify token and words:

let token = w3w.getToken()
let words = w3w.getWords()

w3w.setToken("new-token")
w3w.setWords("///hello.world.test")

LAM projection​

The LAM (Lambert) projection is a conic map projection commonly used for large-scale mapping in regions with an east-west orientation.

Create a LAM projection:

let lam = ProjectionLAMObject(x: 6325113.72, y: 5082540.66)

Access and modify coordinates:

let x = lam.getX()
let y = lam.getY()

print("x=\(x) y=\(y)")

lam.setX(1, setY: 1)

UTM projection​

The UTM (Universal Transverse Mercator) projection is a global map projection that divides the world into a series of zones, each with its own coordinate system.

Create a UTM projection:

let utm = ProjectionUTMObject(x: 6325113.72, y: 5082540.66, zone: 1, hemisphere: .north)

Access and modify values:

let x = utm.getX()
let y = utm.getY()
let zone = utm.getZone()
let hemisphere = utm.getHemisphere()

print("x=\(x) y=\(y) zone=\(zone) hemisphere=\(hemisphere)")

utm.setX(1, setY: 1, zone: 2, hemisphere: .south)

Convert between projections​

ProjectionContext.convert(_:to:completionHandler:) converts from one projection object to another.

let context = ProjectionContext()
let from = ProjectionWGS84Object(
    coordinates: CoordinatesObject.coordinates(withLatitude: 51.5074, longitude: -0.1278)
)
let to = ProjectionMGRSObject(easting: 0, northing: 0, zone: "", letters: "")

let code = context.convert(from, to: to) { result in
    print("conversion result = \(result)")
    print("zone=\(to.getZone()) easting=\(to.getEasting()) northing=\(to.getNorthing())")
}

print("operation started with code = \(code)")
danger

ProjectionContext.convert works with ProjectionW3WObject only if the object has a valid token that can be obtained from what3words.com. If the token is not set or invalid, the conversion will fail and return SDKErrorCodeKNotSupported.

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