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what3words/w3w-swift-wrapper v4.0.0
Swift library for what3words REST API.
⭐️ 24
🕓 4 days ago
iOS macOS watchOS tvOS
.package(url: "https://github.com/what3words/w3w-swift-wrapper.git", from: "v4.0.0")


what3words w3w-swift-wrapper

A swift library to use the what3words REST API, and the what3words VoiceAPI.


The what3words Swift API wrapper gives you programmatic access to

  • convert a 3 word address to coordinates
  • convert coordinates to a 3 word address
  • autosuggest functionality which takes a slightly incorrect 3 word address, and suggests a list of valid 3 word addresses
  • obtain a section of the 3m x 3m what3words grid for a bounding box.
  • determine the currently support 3 word address languages.
  • autosuggest functionality to convert a spoken 3 word address (via voiceAPI) to a list of valid 3 word addresses

The main API swift wrapper object is What3WordsV3 and provides the above functionality. There is also a higher level W3WAutosuggestHelper that does a lot of the work of calling the API for text field autosuggest functionality. This is particularly helpful if you want to add what3words to your existing autocomplete code. A tutorial can be found here.

Even higher level UI functionality can be found in our UI components library, w3w-swift-components, found on GitHub. Notably our W3WAutosuggestTextField inherits UITextField and adds three word address autocomplete functionality.


You can find a short tutorial here that will show you how to get minimally set up and running.


This package also contains an Objective-C compatible version, What3WordsObjC - see the ObjectiveC project in Examples/ObjectiveC/ObjectiveC.xcodeproj

OS Requirements

This package works with:

  • macOS version 10.11 or higher
  • iOS version 9 or higher
  • tvOS version 9 or higher
  • watchOS version 2 or higher


To use this library you’ll need a what3words API key, which can be signed up for here. If you wish to use the Voice API calls then you must add a Voice API plan to your account.


Examples for this package can be ofund in our exmaples repository: https://github.com/what3words/w3w-swift-samples


Swift Package Manager

You can install this with Swift Package Manager by adding the URL below to Swift Packages under your project settings:


CocoaPods (iOS 9+, OS X 10.10+)

You can use CocoaPods to install w3w-swift-wrapper by adding it to the target in your Podfile:

pod 'W3WSwiftApi', :git => 'https://github.com/what3words/w3w-swift-wrapper.git'



In any file you use the what3words API in, import the following:

import W3WSwiftApi
import CoreLocation
Note:src="https://raw.github.com/what3words/w3w-swift-wrapper/master/f you are using CocoaPods use import what3words instead.
  • If you are using this package's Voice API features on device, you should include Microphone permissions:


Use the following code with your API key to initialise the API:

let api = What3WordsV3(apiKey: "YourApiKey")

In the case that you run our Enterprise Suite API Server yourself, you may specify the URL to your own server like so:

let api = What3WordsV3(apiKey: "YourApiKey", apiUrl: "https://api.yourserver.com")

Additionally, if you run the Enterprise Suite API Server there is another optional setup() parameter: customHeaders. Use this if you need to send custom headers to your own server:

let api = What3WordsV3(apiKey: "YourApiKey", apiUrl: "https://api.yourserver.com", customHeaders: ["x-header-1":"value-1", "x-header-2":"value-2"])


Each call takes a completion block as the last parameter. This allows Swift's trailing closure syntax to be used. The closure's parameters contain the results. If there was a problem with any call, it will be indicated by the error object.

Convert To 3 Word Address

Convert coordinates, expressed as latitude and longitude to a 3 word address. This function takes the latitude and longitude as a CLLocationCoordinate2D object. The values returned from the convertTo3wa method are described in the API documentation.

Code Example:
let coords = CLLocationCoordinate2D(latitude: 51.4243877, longitude: -0.34745)
api.convertTo3wa(coordinates: coords, language: W3WApiLanguage(locale: "en")) { square, error in
    print(square?.words ?? "")

Convert To Coordinates

Convert a 3 word address to a position, expressed as coordinates of latitude and longitude. This function takes the words parameter as a string of 3 words 'table.book.chair'. The values returned from the convertToCoordinates method are described in the API documentation.

Code Example:
api.convertToCoordinates(words: "filled.count.soap") { square, error in
  print(square?.coordinates ?? "")


Returns a list of 3 word addresses based on user input and other parameters.

This method provides corrections for the following types of input error:

  • typing errors
  • spelling errors
  • misremembered words (e.g. singular vs. plural)
  • words in the wrong order

The autosuggest method determines possible corrections to the supplied 3 word address string based on the probability of the input errors listed above and returns a ranked list of suggestions. This method can also take into consideration the geographic proximity of possible corrections to a given location to further improve the suggestions returned.

  • voice

If you have a VoiceAPI enabled account, you may also call autosuggest with audio data for voice recognition. In order for this to work, you must add a Voice API plan to your account. There is a minimal example of this below, but detailed information can be found here

Input 3 word address

You will only receive results back if the partial 3 word address string you submit contains the first two words and at least the first character of the third word; otherwise an error message will be returned.

To check if your address string meets this criteria, we provide a simple function that employs our regex to help you recognise the three word addresses. It is called isPossible3wa, but please note that it only indicates if the input is three potential words separated by two w3w separators. It WILL NOT tell you if it is a real three word address in world. The following if evaluates to true.

if api.isPossible3wa(text: "xxx.xxx.x") {
  print("Input is in the form of a three word address")
} else {
  print("Input is NOT in the form of a three word address")

Or if you prefer, you can simply use our regex. Example code can be found in our regex documentation.


We provide various clip policies to allow you to filter by a geographic area. We recommend that you use the clipping to give a more targeted set of results to your user. You can clip by country, or by geographical box, circle or polygon. Do this via the W3WOptions and pass it into the autosuggest call (see example below).


If you know your user’s current location, we also strongly recommend that you use focus to return results which are likely more relevant. Do this via the W3WOptions and pass it into the autosuggest call (see example below)

The values returned from the autosuggest method are described in the what3words REST API documentation.


The first parameter is the partial three words, or voice data. The second optional parameter is the options for the autosuggest function. The last parameter is the completion block.

Example One

api.autosuggest(text: "filled.count.soa") { (suggestions, error) in
  for suggestion in suggestions ?? [] {
    print("\(suggestion.words ?? "") is near \(suggestion.nearestPlace ?? "")")

Example Two

Focus on one particular place using a single option:

let coords = CLLocationCoordinate2D(latitude: 51.4243877, longitude: -0.34745)
api.autosuggest(text: "flottons.annulons.garço", options: W3WOption.focus(coords)) { (suggestions, error) in
  print(suggestions ?? "")

Example Three

Focus on (51.4243877,-0.34745), and clip to the UK using the multiple options object:

let coords = CLLocationCoordinate2D(latitude: 51.4243877, longitude: -0.34745)
let options = W3WOptions().focus(coords).clipToCountry("GB")
api.autosuggest(text: "flottons.annulons.garço", options: options) { (suggestions, error) in
  print(suggestions ?? "")

VoiceAPI Example

The what3words Voice API allows a user to say three words into any application or service, with it returning a configurable list of what3words address suggestions, all through a single API call.

In order for this to work, you must add a Voice API plan to your account.

This example instantiates a W3WMicrophone which provides an audio stream to autosuggest(audio:) which begins recording when autosuggest is called. For information on W3WMicrophone and customizing your own W3WAudioStream for autosuggest(audio:) see the VoiceAPI README.

// make a microphone
let microphone = W3WMicrophone()

// call autosuggest
api.autosuggest(audio: microphone, options: .voiceLanguage(W3WApiLanguage(locale: "en"))) { suggestions, error in
  for suggestion in suggestions ?? [] {
    print(suggestion.words ?? "no suggestions")

Also, W3WMicrophone has a callback closure W3WMicrophone.volumeUpdate: (Double) -> () that provides amplitude information useful for animating user feedback. See the the Voice API example, and more information is avialable in the VoiceAPI README.

Available Languages

This function returns the currently supported languages for text based autosuggest(text:) calls. It will return the two letter code (ISO 639), and the name of the language both in that language and in English.

The values returned from the convertTo3wa method are described in the what3words REST API documentation

Code Example

api.availableLanguages() { (languages, error) in
  for language in languages ?? [] {
    print(language.code, language.name, language.nativeName)

For the available Voice API languages call api.availableVoiceLanguages(completion:) which works exactly the same way.

Grid Section

Returns a section of the 3m x 3m what3words grid for a given area. The requested box must not exceed 4km from corner to corner, or a BadBoundingBoxTooBig error will be returned. Latitudes must be >= -90 and <= 90, but longitudes are allowed to wrap around 180. To specify a bounding-box that crosses the anti-meridian, use longitude greater than 180. Example value: 50.0, 179.995, 50.01, 180.0005.

The grid is returned as [W3WLine]? and each W3WLine contains a start and end variable, both of type CLLocationCoordinate2D.

The values returned from the gridSection function are described in the what3words REST API documentation

Code Example

let southWest = CLLocationCoordinate2D(latitude: 52.208867, longitude: 0.117540)
let northEast = CLLocationCoordinate2D(latitude: 52.207988, longitude: 0.116126)

api.gridSection(southWest: southWest, northEast: northEast) { (lines, error) in
  for line in lines ?? [] {
    print(line.start, " -> ", line.end)

Validation Functions

These are some functions that will search or validate three word addresses.

isPossible3wa(text: String) -> Bool

Checks to see if the text follows the form of a three word address via regex, that is, a word followed by a separator followed by a word followed by a separator followed by a word. A word is defined as series of letters that belong to any writing system. This does not validate the address as being a real location on the earth, just that it follows the textual form of one. For example, xx.xx.xx would pass this test even though it is not a valid address.

if api.isPossible3wa(text: "abc.def.ghi") {
  print("does match the text pattern for a three word address")

This would print the result because even though "abc.def.ghi" is not a valid three word address, still it does fit the form of one, [word][separator][word][separator][word].

isValid3wa(words: String, completion: @escaping (Bool) -> ())

Verifies that the text is a valid three word address that successfully represents a square on earth. This makes a call to the API to verify. The other validation functions only run a regex locally.

api.isValid3wa(words: "filled.count.soap") { valid in
  if valid {
    print("the address provided is a real address somewhere on earth")

findPossible3wa(text: String) -> [String]

Finds any number of possible three word addresses in a block of text. The term "possible three word addresses" refers to text that matches the regex used in isPossible3wa(), that is, these are pieces of text that appear to be three word address, but have not been veified against the engine as representing an actual place on earth.

let twas = api.findPossible3wa(text: "This is a filled.count.soap sentence with index.home.raft fun in it nowhere near grilled.cheese.sandwhich")

This will print out: ["filled.count.soap", "index.home.raft", "grilled.cheese.sandwhich"]

Handling Errors

All functions call the completion block with error as the second parameter. All Swift what3words error are W3WError and conform to CustomStringConvertible, so they can be used with String(describing: error), and they also conform to Error of course:

Code Example

api.convertTo3wa(coordinates: CLLocationCoordinate2D(latitude: 51.4243877, longitude: -0.34745)) { square, error in
  if let e = error {
    print(String(describing: e))
  } else {
    print(square?.words ?? "")

Api call errors are of type W3WError enum and the voice autosuggest call returns a W3WVoiceError enum.

SDK Compatibility

There is also an SDK that works offline. More information is available here.

The SDK can be used interchangeably with this API wrapper. That is, you can start your project using this API wrapper, and you can later upgrade to the SDK with minimal changes to your code.

Below is a table of which SDK version is compatible with which API wrapper version:

w3w-swift-wrapper SDK Version
v3.8.2 and lower v3.8.0 and lower
v3.9.0 and higher v4.0.0 and higher


Stars: 24
Last commit: 4 days ago
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