Geohash is a public domain geocode system invented in 2008 by Gustavo Niemeyer and (similar work in 1966) G.M. Morton, which encodes a geographic location into a short string of letters and digits. It is a hierarchical spatial data structure which subdivides space into buckets of grid shape, which is one of the many applications of what is known as a Z-order curve, and generally space-filling curves.
Geoflash is performance tested against other Swift implementations of the geohash algorithm. It is intended to perform well when compared to others and be a single file solution.
- A base implementation using
Doubleprimitives for arguments to be easily integrated into other types as extensions
- A general purpose geodesy framework
Via Swift Package Manager
The unit tests demonstrate proper usage for common scenarios and are repeated below for quick skim read purposes.
To hash a location simply pass the latitude and longitude as Double to the encode(latitude:longitude) static function.
let hash = try Geoflash.encode(latitude: 38.897, longitude: -77.036)
// dqcjr0bp7n74Optionally a precision argument can be passed to limit the length of the hash and correspondingly limit the precision should the hash be decoded. The default for precision is 12.
let hash = try Geoflash.encode(latitude: 38.897, longitude: -77.036, precision: 5)
// dqcjrThe following is a sample usage to decode a 12 digit geohash. A 12 digit hash has sufficient resolution to allow for the returning of a single GeoJSON point.
let hash = "63tn3q5d84bp" // Talca, South America
let points = try Geoflash.decode(geohash: hash)
// [[-71.65901184082031, -35.43046312406659]]
// Latitude: -35.43046312406659
// Longitude: -71.65901184082031The maxPointDistance parameter can optionally be passed in to control what level of accuracy is required from the output (or the range of values in other words). The default value is a value of 0.000001 which has the effect of returning a single point for hashes of 12 digits and a polygon drawing the range of values for all lower lengths of hash.
let hash = "63tn3q"
let points = try Geoflash.decode(geohash: hash)
// [[-71.663818359375, -35.430908203125], [-71.65283203125, -35.430908203125], [-71.65283203125, -35.4254150390625], [-71.663818359375, -35.4254150390625]]