HTTP communication with Swift

HTTP communication with Swift

• Contents
  • HTTP communication
  • HTTP communication in iOS
  • Practice 1
  • Codadble
  • Practice 2

HTTP communication

• HTTP communication

  • HTTP(Hyper Text Transfer Protocol)
  • You should follow this protocol to communicate on internet

• Major HTTP method

  • GET: Get data from server
  • POST: Create data on server
  • PUT: Update data on server
  • DELETE: Delete data on server

• Slack

  • 
  • 
  • 

• CURL

  • A library to transfer data from the commandline or script
  • 
  • 

HTTP communication in iOS

• Frameworks

  • 1. Foundation
  • 2. CFNetwork
  • 3. Core OS(Darwin)

• What we use..?

  • Foundation
    • URLSession

• URLSession

  • Multithreaded iOS APIs
  • URLSessionDataTask
    • A URL session task that returns downloaded data directly to the app in memory.
  • URLSessionDownloadTask
    • A URL session task that stores downloaded data to a file.
  • URLSessionUploadTask
    • A URL session task that uploads data to the network in a request body.

// https://developer.apple.com/documentation/foundation/url_loading_system/fetching_website_data_into_memory
// Listing 1: Creating a completion handler to receive data-loading results

func startLoad() {
    let url = URL(string: "https://www.example.com/")!
    let task = URLSession.shared.dataTask(with: url) { data, response, error in
        if let error = error {
            self.handleClientError(error)
            return
        }
        guard let httpResponse = response as? HTTPURLResponse,
            (200...299).contains(httpResponse.statusCode) else {
            self.handleServerError(response)
            return
        }
        if let mimeType = httpResponse.mimeType, mimeType == "text/html",
            let data = data,
            let string = String(data: data, encoding: .utf8) {
            DispatchQueue.main.async {
                self.webView.loadHTMLString(string, baseURL: url)
            }
        }
    }
    task.resume()
}

Practice 1

import Foundation

func sendHTTPRequest() {
    guard let url = URL(string: "https://hooks.slack.com/services/") else { return }
    
    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "POST"
    urlRequest.httpBody = #"payload={"text":"hello, world"}"#.data(using: .utf8)!
    
    URLSession.shared.dataTask(with: urlRequest).resume()
}

sendHTTPRequest()
RunLoop.current.run(until: .now + 1)

Codable

• Codable
  • A type that can convert itself into and out of an external representation
  • You can make your data type encodable and decodable for Property list(plist) or JSON

// https://developer.apple.com/documentation/foundation/archives_and_serialization/encoding_and_decoding_custom_types

struct Landmark: Codable {
    var name: String
    var foundingYear: Int
    
    // Landmark now supports the Codable methods init(from:) and encode(to:), 
    // even though they aren't written as part of its declaration.
}

• JSON(JavaScript Object Notation)
  • A lightweight data-interchange format
  • It is easy for humans to read and write
  • It is easy for machines to parse and generate

Practice 2

import Foundation

struct Message: Codable {
    let text: String
}

func sendHTTPRequest() {
    let message = Message(text: "hi, smile")
    guard let url = URL(string: "https://hooks.slack.com/services/") else { return }
    guard let data = try? JSONEncoder().encode(message) else { return }
    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "POST"
    urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
    urlRequest.httpBody = data
    
    URLSession.shared.dataTask(with: urlRequest).resume()
}

sendHTTPRequest()
RunLoop.current.run(until: .now + 1)