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Lightweight REST API communicator written in Swift, based on Foundation


Lightweight REST API communicator written in Swift, based on Foundation. An easy tool to communicate with your server's API in JSON format. Supports querys and valid JSON objects in the HTTP body.

Carthage compatible

The framework supports GET, POST, PUT and DELETE requests for now.

PATCH is added at 0.6.0, maybe it's not so RESTful, but you have it.


Swift Package Manager

.package(url: "https://github.com/Gujci/RESTAPI.git")

In dependenciec add RESTAPI or RESTAPIImage as well for Image upload & other image related extensions.


github "Gujci/RESTAPI"

Carthage dropped support for multiple frameworks / repo, so it has to be compiled on device to be able to use both RESTAPI and RESTAPIImage for Image upload.

RESTAPIImage is a sepatate framework, in order to use, add it to Carthage copy-frameworks phase and link it.

This framework highly relies on [SwiftyJSON] (https://github.com/SwiftyJSON/SwiftyJSON), so it imports it.

Older versions

Swift 2.2

for Swift 2.2 use the 0.2.2 tag. This version will not be supported.

github "Gujci/RESTAPI" "== 0.2.2"

Swift 3

for Swift 3 use the 0.6.1 tag. This version will not be supported.

github "Gujci/RESTAPI" "== 0.6.1"


For the latest verion, use

pod 'RESTAPI', :git => 'https://github.com/Gujci/RESTAPI.git'



Basic request

By default you can perform a single request which returns a simple JSON response.

let testServerApi = API(withBaseUrl: "http://jsonplaceholder.typicode.com")
testServerApi.get("/posts") { (status, data: JSON?) in
    //This data will be SwiftyJSON's Optional JSON type

Or if you want to, you can get a parsed response type with the same request.

Request with expected response type

First you have to implement your response type, which must comform to JSONParseable protocol.

struct ExampleResponse: JSONParseable {
    var body: String
    var id: Int
    var title: String
    var userId: Int
    init(withJSON data: JSON) {
        body = data["body"].stringValue
        id = data["id"].intValue
        title = data["title"].stringValue
        userId = data["userId"].intValue

JSONParseable is a convinience protocol, which inherits from ValidResponseData. Custom ValidResponseData can also be implemented, and requested.

Or by using Codable

By conforming to Decodable , the given type automatically conforms to JSONCodable, which is ValidResponseData.

struct ExampleResponse: Codable {
    var body: String
    var id: Int?
    var title: String
    var userId: Int

extension ExampleResponse: JSONCodable {}

After implementing the response object, you have to set the type of the expected response data in the completion's parameter list like this.

testServerApi.get("/posts") { (status, data: [ExampleResponse]?) in
    //This a swift array now, filled with ExampleResponse instances

In this case an array was expected as response, but simple types will work as well (like ExampleResponse?). It's important that you mark your parameter as optional, otherwise you will get a compile time error.


Querying is simple like this:

testServerApi.get("/posts", query: ["userId" : "1"]) { (status, object: [ExampleResponse]?) in

Values in the query parameter dictionary must implement the Queryable protocol, String and Array types implement this by default.

Body parameters

Simple body

testServerApi.post("/posts", data: ["body": "something","id": 1, "title": "Some title", "userId": 9]) { (status, object) in

Body parameters should comform to ValidJSONObject protocol. Array and Dictionary types implement this by default. Any custom type can implement ValidJSONObject, which requres a function that converts your type to Data.

func JSONFormat() throws -> Data

Custom object in body without Codable

If you don't want that much controll and resposibility, you can implement JSONConvertible, which has a property named parameterValue which can be any ValidJSONObject. Practically you just have to convert your type to a Dictionary or an other ValidJSONObject just it like this:

struct ExampleData {
    var body: String
    var id: Int
    var title: String
    var userId: Int

extension ExampleData: JSONConvertible {
    // this is valid json
    var parameterValue: [String: Any] {
        return ["body": body, "id": id, "title": title, "userId": userId]

Additional fields can be added anytime to this property, also, you can exclude any properties.

Custom object in body with Codable

By conforming to ValidJSONData, Encodable types are automatically parsed to a request json, no manual step needed.

struct ExampleData: Codable {
    var body: String
    var id: Int?
    var title: String
    var userId: Int

extension ExampleData: ValidJSONData {}


To upload, just pass a ValidRequestData to the approptiate function's data parameter.

var uploadData = ExampleData(body: "body", id: 1, title: "title", userId: 2)

testServerApi.post("/posts", data: uploadData) { (status, object: JSON?) in

Form encoded request

The framework also supports form-encoded requests as long as the response is in JSON format. To send one use a similar json request, but the body must comform to ValidFormData protocol.

If you want to save time, and ok with simple [String: String] format, just implement the FormEncodable protocol, which is much easyer and automatically conform to ValidFormData.

Dictionary has an added element called formValue, which is automatically conforms to ValidFormData. This is mostly a workaruond for a problem described later

extension ExampleData: FormEncodable {

var parameters: [String: String] {
        return ["body": body, "id": "\(id)", "title": title, "userId": "\(userId)"]

// ...
oldServerApi.post("/post.php", query: ["dir": "gujci_test"], data: uploadData.formValue){ (status, response: JSON?) in
    // ... do something

No Codable support for form encoded request yet.

Multipart form request

MultipartFormData is a protocol, which provides default implementation for ValidRequestData. Implement this protocol to prepare any custom type to be uploaded as multipart form data.


Cacheable is a protocol, which can be used with the load() function of API. This enables responses (eq. images) to be cached on device. The implementation is up to the developer, on order the conform to Cacheable a type must implement the following methods.

static func getPersistantData(for url: String) throws -> Self?

func savePersistant(for url: String) throws

Since the only key for cache is the URL string itself, this mechanism is better for binaries like images and data, where the URL is also an identifier for a resource.


There is a separate target called RESTAPIImage, which contains upload and cached download implementations to supported protocols ( Cacheable, MultipartFormData ) for UIImage.

It also contains an extension for UIImageView to just pass an URL to it to set up the image:

func setup(from imageUrl: String?)

UIImage extensions only work in environments, where UIKit is available.

Image upload

RESTAPIImage adds a util implementation for MultipartFormData to upload a simple image. To perform an upload, just instantiate a new JPGUploadMultipartFormData instance with UIImage and send it as any other request.

let uploadData = JPGUploadMultipartFormData(image: image, fileName: "image", uploadName: "upfile")
api.post("/me/profile_picture", data: uploadData) { (status, resp: JSON?) in 

As all methods requre a ValidRequestData to send in body, uploading JPGUploadMultipartFormData is not different from any json upload besides composing the httpBody of the request. Any utils like authentication can be used, the response parsing is the same.

If the JPGUploadMultipartFormData implemetation is not suited for the current usecase, custom implemetnation for MultipartFormData can be implemented easily, like described before

Authenticating requests

To authenticate a request, you have to set the authentication property of the API instance. For now this framework supports simple, access token based authentications in HTTP header and URL query. This is a simple example to show how to set up a HTTP header based authentication.

var accessToken: String?

var sessionAuthenticator: RequestAuthenticator {
    let auth = RequestAuthenticator()
    auth.tokenKey = "access_token"
    if let validToken = self.accessToken {
        auth.type = .HTTPHeader
        auth.accessToken = validToken
    else {
        auth.type = .None
    return auth
    testServerApi.authentication = sessionAuthenticator

General body protocol

Any request body sent, must conform to ValidRequestData protocol. The 2 mentioned above are just some pre-implemented, widely used cases. If you use a custom protocol, or something, which is not implemented in this framework, just made the desired types conform to ValidRequestData, and they can be automatically used with the framework.

public protocol ValidRequestData {
    // defines the content type header
    func type() -> ContentType
    // returns the data, to sent to server
    func requestData() throws -> Data

One type must not implement this protocol twice or more, meaning it is not supported to conform to both ValidFormData and JSONConvertible.


A response wrapper is provided in the framework for all ValidResponseData in order to parse both the success and a possible error response. However, using the same structure, you can implement any other type of generic response to match your needs. An example call with the built in one looks like the following:

testServerApi.get("/endpoint") { (status, response: Response<ExampleResponse, APIError>?) in

Where APIError is an other custom ValidResponseData type, but JSON is accepted as well (since it also conforms to ValidResponseData). Note, that array of ValidResponseData also conforms to ValidResponseData.


This section is about one possibble implementation to support Result as a callback type. These are just to suggestions to implement your own. I just put this feature on the roadmap, so hopefully, full support will be coming soon. Also keeping an eye on async/await proposals.

Since swift 5 you may use the Result type as a built in solution to wrap data and error together. You may write an extension like this to be able to use the type, but it would not represent the network error only the one which may occure while parsing the response.

extension Result: ValidResponseData where Success: ValidResponseData {

    public static func createInstance(from data: Data) throws -> Result<Success, Failure> {
        do {
            return .success(try Success.createInstance(from: data))
        catch let e as Failure {
            return .failure(e)

To make full advantage of the type the whole callback should have one Result parameter. Like the following, where SomeResultType can be any compatible type. Also, you may write your own SomeErrorType or just use APIError.

testServerApi.get("/posts") { (data: Result<SomeResultType, SomeErrorType>) in
    // ...

To be able to call this, you have to write a wrapper for the original function.

extension API {

    public func get<T: ValidResponseData, E: Error>(_ endpoint: String, query: [String: Queryable]? = nil, data: ValidRequestData? = nil,
        completion: @escaping (Result<T, E>) -> ()) {
            get(endpoint, query: query, data: data) { (status, response: Data?) in
                // parse status & response to Result
                if status.isSuccess,
                    let response = response,
                    let result = try? T.createInstance(from: response) {
                    } else {
                        // ... custom error parsing


To turn on request logging add APIRequestLoggingEnabled to 'Arguments passed on launch' at Schema/Run/Arguments.

To log server sent errrors turn on APIErrorLoggingEnabled.

TODO list


  • ☑ Document the authentication
  • ☑ Carthage support
  • ☑ CocoaPods support
  • ☑ SPM support
  • ☑ Expand status types to almost full
  • ☑ Make JSON and [JSON] comform to JSONParseable to reduce redundant code (Solved by adding ValidResponseData & Conditional Conformance)
  • Travis GitHub Actions
  • ☑ Document form-encoded-support related changes
  • ☐ Full support for some Result type


Stars: 7
Last commit: 17 weeks ago

Related Packages



Package manager fixes - 2019-10-10T20:07:20

  • Fixes missing files error from Carthage builds
  • Only adds Image extensions where available