Build Status

Generate swift code for any specific GraphQL schema that provides query builders and response classes.


The code generator requires ruby version 2.1 or later.

Until this project is released, it is recommended to include it into a project as a git submodule.

$ git submodule

It is recommended to use bundler to install the code generators ruby package.

Add this line to your application's Gemfile:

gem 'graphql_swift_gen', path: 'graphql_swift_gen'

And then execute:

$ bundle

The generated code depends on support/Sources/GraphQL.swift from this repo which should be added to the project along with the generated code.


Create a script that generates the code for a GraphQL API

require 'graphql_swift_gen'
require 'graphql_schema'
require 'json'

introspection_result ="graphql_schema.json")
schema =,
  nest_under: 'ExampleSchema',
  custom_scalars: [
      type_name: 'Money',
      swift_type: 'NSDecimalNumber',
      deserialize_expr: ->(expr) { "NSDecimalNumber(string: #{expr}, locale: GraphQL.posixLocale)" },
      serialize_expr: ->(expr) { "#{expr}.description(withLocale: GraphQL.posixLocale)" },

That generated code depends on the GraphQLSupport package.

The generated code includes a query builder that can be used to create a GraphQL query in a type-safe mannar.

let queryString = ExampleSchema.buildQuerya { $0
    .user { $0

The generated code also includes response classes that will deserialize the response and provide methods for accessing the field data with it already coerced to the correct type.

guard let response = try? GraphQLResponse<ExampleSchema.QueryRoot>(jsonData: response) else {
    print("Invalid GraphQL response")
if let errors = response.errors {
    for error in errors {
        print("GraphQL error: \(error.message)")
if let data = {
    let user = data.user
    print("\(user.firstName) \(user.lastName)")


After checking out the repo, run bundle to install ruby dependencies. Then, run rake test to run the tests.

To install this gem onto your local machine, run bundle exec rake install or reference it from a Gemfile using the path option (e.g. gem 'graphql_swift_gen', path: '~/src/graphql_swift_gen').


See our contributing guidelines for more information.


The gem is available as open source under the terms of the MIT License.