Rest API calling using RxSwift.

Today, I am going to show how to call rest API using RxSwift. Before the start, we need to know some concept in RxSwift. RxSwift is the swift implementation of popular Reactive Extensions (Rx) library created by Microsoft.

What is Reactive programming?

Reactive programming is an declarative programming paradigm concerned with data streams and the propagation of change. This means that it becomes possible to express static (e.g. arrays) or dynamic (e.g. event emitters) data streams with ease via the employed programming language(s).

— https://en.wikipedia.org/wiki/Reactive_programming.

1. Observables: is like a function with some special characters.

2.Observer: Observables produce some result according to data or action. This Result is called the Observer.

For example: .subscribe(next, error, complete)

Here subscribe is Observableandnext, error, complete are Observer.

3.DisposeBag: This is used to deinit() Observer objects from the memory.

Let start the implementation of RxSwift.

Step 1: Create a new project and pod file

Add RxSwift and RxCocoa in your pod file and install the pod.

# Podfile
use_frameworks!

target 'YOUR_TARGET_NAME' do
    pod 'RxSwift', '~> 5'
    pod 'RxCocoa', '~> 5'
end

# Podfile

use_frameworks!

target 'YOUR_TARGET_NAME' do

pod 'RxSwift', '~> 5'

pod 'RxCocoa', '~> 5'

end

Step 2: Creare a Model Class

struct countryModel: Codable {
    let code: Int?
    let result: [countryListModel]?
    
    private enum CodingKeys: String, CodingKey {
        case code
        case result
    }
}
struct countryListModel: Codable {
    let code: String
    let name: String
    
    private enum CodingKeys: String, CodingKey {
        case code
        case name
    }
}

struct countryModel: Codable {

let code: Int?

let result: [countryListModel]?

private enum CodingKeys: String, CodingKey {

case code

case result

}

struct countryListModel: Codable {

let code: String

let name: String

private enum CodingKeys: String, CodingKey {

case code

case name

}

Step 3: Create an API Request

Create an enum for request type which is helping to manage the API request Type.

public enum RequestType: String {
    case GET, POST, PUT,DELETE
}

public enum RequestType: String {

case GET, POST, PUT,DELETE

}

Create a class for API Request

class APIRequest {
    let baseURL = URL(string: "https://api.printful.com/countries")!
    var method = RequestType.GET
    var parameters = [String: String]()
}

class APIRequest {

let baseURL = URL(string: "https://api.printful.com/countries")!

var method = RequestType.GET

var parameters = [String: String]()

}

Configure the API request.

 func request(with baseURL: URL) -> URLRequest {
       var request = URLRequest(url: baseURL)
        request.httpMethod = method.rawValue
        request.addValue("application/json", forHTTPHeaderField: "Accept")
        return request
    }

func request(with baseURL: URL) -> URLRequest {

var request = URLRequest(url: baseURL)

request.httpMethod = method.rawValue

request.addValue("application/json", forHTTPHeaderField: "Accept")

return request

}

Now calling API.

class APICalling {
    // create a method for calling api which is return a Observable
    func send<T: Codable>(apiRequest: APIRequest) -> Observable<T> {
        return Observable<T>.create { observer in
            let request = apiRequest.request(with: apiRequest.baseURL)
            let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
                do {
                    let model: countryModel = try JSONDecoder().decode(countryModel.self, from: data ?? Data())
                    observer.onNext( model.result as! T)
                } catch let error {
                    observer.onError(error)
                }
                observer.onCompleted()
            }
            task.resume()
            
            return Disposables.create {
                task.cancel()
            }
        }
    }
}

class APICalling {

// create a method for calling api which is return a Observable

func send<T: Codable>(apiRequest: APIRequest) -> Observable<T> {

return Observable<T>.create { observer in

let request = apiRequest.request(with: apiRequest.baseURL)

let task = URLSession.shared.dataTask(with: request) { (data, response, error) in

do {

let model: countryModel = try JSONDecoder().decode(countryModel.self, from: data ?? Data())

observer.onNext( model.result as! T)

} catch let error {

observer.onError(error)

}

observer.onCompleted()

}

task.resume()

return Disposables.create {

task.cancel()

}

Step 4: Create an APICalling class and DisposeBag object.

private let apiCalling = APICalling()
private let disposeBag = DisposeBag()

1 2	private let apiCalling = APICalling() private let disposeBag = DisposeBag()

Load TableView after API call.

tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
let request =  APIRequest()
let result : Observable<[countryListModel]> = self.apiCalling.send(apiRequest: request)
_ = result.bind(to: tableView.rx.items(cellIdentifier: "cell")) { ( row, model, cell) in
   cell.textLabel?.text = model.name
}

tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")

let request = APIRequest()

let result : Observable<[countryListModel]> = self.apiCalling.send(apiRequest: request)

_ = result.bind(to: tableView.rx.items(cellIdentifier: "cell")) { ( row, model, cell) in

cell.textLabel?.text = model.name

}

I hope it will help everyone.

Debabrata Roy 31 May 2019

. . .

3 comments

Armughangul Aug 19, 2019 at 1:23 pm

brilliant article

Dave Chambers Aug 7, 2020 at 3:56 am

Great post Debabrata – very interesting!

Rahul Jamba Mar 21, 2022 at 7:09 pm

Great Post, very simple explanation !!!!!!!!!!

Rest API calling using RxSwift.

What is Reactive programming?

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