How to make an API call with Swift? - swift

Question

So I'm practising trying to make API calls with Swift. The code is as below:
struct Example: Codable {
let userID: String
let ID: String
let title: String
let completed: String
}
func getJson(completion: #escaping (Example)-> ()) {
let urlString = "https://jsonplaceholder.typicode.com/todos/1"
if let url = URL(string: urlString) {
URLSession.shared.dataTask(with: url) {data, res, err in
if let data = data {
let decoder = JSONDecoder()
if let json: Example = try? decoder.decode(Example.self, from: data) {
completion(json)
}
}
}.resume()
}
}
getJson() { (json) in
print(json.ID)
}
However, I am unable to print out anything when getJson is called.
The example API I used is found here.
The tutorial that I used to help me write the code is found here.

Answer 1

Modified your variable name and data type exactly as your API response.
struct Example: Codable {
let userId: Int
let id: Int
let title: String
let completed: Bool
}
func getJson(completion: #escaping (Example)-> ()) {
let urlString = "https://jsonplaceholder.typicode.com/todos/1"
if let url = URL(string: urlString) {
URLSession.shared.dataTask(with: url) {data, res, err in
if let data = data {
let decoder = JSONDecoder()
do {
let json: Example = try! decoder.decode(Example.self, from: data)
completion(json)
}catch let error {
print(error.localizedDescription)
}
}
}.resume()
}
}
getJson() { (json) in
print(json.id)
}
You can also use CodingKey and can change your response during the init period.
struct Example: Codable {
var userID: Int
var ID: Int
var title: String
var completed: Bool
enum CodingKeys: String, CodingKey {
case userID = "userId"
case ID = "id"
case title = "title"
case completed = "completed"
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
userID = try values.decode(Int.self, forKey: .userID)
ID = try values.decode(Int.self, forKey: .ID)
title = try values.decode(String.self, forKey: .title)
completed = try values.decode(Bool.self, forKey: .completed)
title = "Title: \(title)"
}
}
func getJson(completion: #escaping (Example)-> ()) {
let urlString = "https://jsonplaceholder.typicode.com/todos/1"
if let url = URL(string: urlString) {
URLSession.shared.dataTask(with: url) {data, res, err in
if let data = data {
do {
let json: Example = try JSONDecoder().decode(Example.self, from: data)
completion(json)
}catch let error {
print(error.localizedDescription)
}
}
}.resume()
}
}
getJson() { (json) in
print("ID: \(json.ID) \(json.title)")
}

Answer 2

import UIKit
class ApiManager: NSObject {
static func postApiRequest(url: String,parameters:[String: Any],completion: #escaping([String: Any])-> Void) {
let session = URLSession.shared
let request = NSMutableURLRequest(url: NSURL(string: url)! as URL)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
do{
request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: JSONSerialization.WritingOptions())
let task = session.dataTask(with: request as URLRequest as URLRequest, completionHandler: {(data, response, error) in
if let response = response {
let nsHTTPResponse = response as! HTTPURLResponse
let statusCode = nsHTTPResponse.statusCode
print ("status code = \(statusCode)")
}
if let error = error {
print ("\(error)")
}
if let data = data {
do{
let jsonResponse = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions())
print ("data = \(jsonResponse)")
}catch _ {
print ("OOps not good JSON formatted response")
}
}
})
task.resume()
}catch _ {
print ("Oops something happened buddy")
}
}
}