I know that Codable = Decodable & Encodable but when calling json from xcode,
Codable was given as a struct, but an error saying
Argument type'login.Type' does not conform to expected type'Encodable' appears.
json code
struct login: Codable {
var userId: String?
var userPw: String?
class func LoginBoard(_ completeHandler: #escaping (login) -> Void) {
let loginboard: String = MAIN_URL + "/member/login"
guard let url = URL(string: loginboard) else {
print("Error: cannot create URL")
return
}
var urlRequest = URLRequest(url: url)
urlRequest.httpMethod = "POST"
urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
urlRequest.addValue("application/json", forHTTPHeaderField: "Accept")
urlRequest.httpBody = try? JSONEncoder().encode(login) // ERROR [Argument type 'login.Type' does not conform to expected type 'Encodable']
let session = URLSession.shared
let task = session.dataTask(with: urlRequest) { (data, response, error) in
guard error == nil else {
print("error calling Post on /todos/1")
print(error!)
return
}
guard let responseData = data else {
print("Error: did not receive data")
return
}
do {
let decoder = JSONDecoder.init()
let LoginList = try decoder.decode(login.self, from: responseData)
completeHandler(LoginList)
}
catch {
print("error trying to convert data to JSON")
return
}
}
task.resume()
}
There is no error in try decoder.decode
but only in urlRequest.httpBody = try? JSONEncoder().encode(login) what is the problem?
You need to have something like this to set the values.
let loginvalues = login(userId: "john", userPw: "adfadfa")
urlRequest.httpBody = try? JSONEncoder().encode(loginvalues)
If you place this inside a play ground and run it you will see that you get the json data.
struct Login: Codable {
var userId: String?
var userPw: String?
}
let loginvalues = Login(userId: "john", userPw: "adfadfa")
let test = try? JSONEncoder().encode(loginvalues)
print(String(data: test!, encoding: .utf8)!)
Related
I'm using a generic function for POST requests in my app. I have the following function:
func PostRequest<In:Codable>(object: In, endpoint: String){
do{
let url = URL(string: "http://localhost:8080/\(endpoint)/")
var request = URLRequest(url: url!)
request.httpMethod = "POST"
request.httpBody = try JSONEncoder().encode(object)
URLSession.shared.dataTask(with: request) {data, response, error in
guard let data = data, error == nil else{
print(error?.localizedDescription ?? "No Data")
return
}
let JSONResponse = try? JSONSerialization.jsonObject(with: data, options: [])
if let JSONResponse = JSONResponse as? [String: Any] {
print(JSONResponse)
}
}.resume()
}catch{
print(error)
}
}
And in this case, the object is the following struct:
struct MarkAsDelivered: Codable{
let whoCollected: String
let deliveryID: Int
}
When I print the result of JSONEncoder().encode(object) as a string, it returns the following, as would be expected:
{
"whoCollected":"TESTNAME",
"deliveryID":140
}
however, when i view this JSON object on my backend, it returns it as the following:
{
"{\"whoCollected\":\"TESTNAME\",\"deliveryID\":140}" : ""
}
From what I can tell, it is using the JSON object as a key.
Does anyone know what has caused this issue. Any assistance would be greatly appreciated.
as #burnsi mentioned in the comments to my question, I was indeed missing the content type. Specifying it fixed my issue:
func PostRequest<In:Codable>(object: In, endpoint: String){
do{
let url = URL(string: "http://localhost:8080/\(endpoint)/")
var request = URLRequest(url: url!)
request.httpMethod = "POST"
//Added content type on line below:
request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
request.httpBody = try JSONEncoder().encode(object)
URLSession.shared.dataTask(with: request) {data, response, error in
guard let data = data, error == nil else{
print(error?.localizedDescription ?? "No Data")
return
}
let JSONResponse = try? JSONSerialization.jsonObject(with: data, options: [])
if let JSONResponse = JSONResponse as? [String: Any] {
print(JSONResponse)
}
}.resume()
}catch{
print(error)
}
}
I have the following Struct that I want to initialize, and then use its method query() to mutate its result property.
Query() sends and fetches JSON data, then decodes it to a String. When I declare query() as a mutating function, I receive the error "Escaping closure captures mutating 'self' parameter" in my URLSession.
What do I need to change?
The call:
var translation = Translate(string: "hello", base: "en", target: "de", result: "")
translation.query()
let translated = translation.result
The struct:
struct Translate {
let string: String, base: String, target: String
var result: String
mutating func query() {
let body: [String: String] = ["q": self.string, "source": self.base, "target": self.target]
let bodyData = try? JSONSerialization.data(withJSONObject: body)
guard let url = URL(string: "https://libretranslate.com/translate") else { return }
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = bodyData
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
URLSession.shared.dataTask(with: request) { data, response, error in
guard let data = data, error == nil else {
print(error?.localizedDescription ?? "No data")
return
}
DispatchQueue.main.async {
let responseJSON = try? JSONSerialization.jsonObject(with: data, options: [])
if let responseJSON = responseJSON as? [String: Any] {
if responseJSON["translatedText"] != nil {
self.result = responseJSON["translatedText"] as! String
}
}
}
return
}
.resume()
}
}
Xcode error:
There are many issues in the code.
The most significant issue is that the URLRequest is asynchronous. Even if no error occurred result will be always empty.
You have to add a completion handler – it fixes the errors you got by the way – and it's highly recommended to handle all errors.
Instead of JSONSerialization the code uses JSONDe/Encoder
struct Translation : Decodable { let translatedText : String }
struct Translate {
let string: String, base: String, target: String
func query(completion: #escaping (Result<String,Error>) -> Void) {
let body: [String: String] = ["q": self.string, "source": self.base, "target": self.target]
do {
let bodyData = try JSONEncoder().encode(body)
let url = URL(string: "https://libretranslate.com/translate")!
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = bodyData
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
URLSession.shared.dataTask(with: request) { data, response, error in
if let error = error { completion(.failure(error)); return }
completion( Result{ try JSONDecoder().decode(Translation.self, from: data!).translatedText} )
}
.resume()
} catch {
completion(.failure(error))
}
}
}
let translation = Translate(string: "hello", base: "en", target: "de")
translation.query() { result in
DispatchQueue.main.async {
switch result {
case .success(let translated): print(translated)
case .failure(let error): print(error)
}
}
}
Both exclamation marks (!) are safe.
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.
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)")
}
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")
}
}
}
Hi I'm new to Swift and I am trying to create a reusable generic Download Manager for URL Request that can be reused throughout my project in different View Controllers or reused within the same VC for a different URL Request calls. The problem that I have is how do I pass the Data Type from the Request into the Download Manager and then return the Downloaded Data back to the VC with the corresponding Data Type. I am able to pass the Data Type in a call to downloadRequest but I can't figure out how to pass the Data Type back to the VC via a delegate DownloadManagerDelegate. Any help would be greatly appreciate it!
Generic Download Manager:
protocol DownloadManagerDelegate {
func didUpdateData<T: Codable>(modelType: T.Type, downloadedData: T.Type)
}
struct DownloadManager {
var delegate: DownloadManagerDelegate?
func downloadRequest<T: Codable>(modelType: T.Type, parameters: [String: Any]) {
guard let url = URL(string: "https://www.someAPI...") else {return}
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
guard let httpBodyWithParameters = try? JSONSerialization.data(withJSONObject: parameters, options: []) else
{
print("error")
return
}
request.httpBody = httpBodyWithParameters
let session = URLSession.shared
session.dataTask(with: request) { (data, response, error) in
if error != nil {
print("error")
return
}
if let safeData = data {
if let downloadedData = parseDownloadedData(data: safeData) {
self.delegate?.didUpdateData(modelType: modelType, downloadedData: downloadedData)
}
}
}.resume()
func parseDownloadedData(data: Data) -> T?{
let decoder = JSONDecoder()
do {
let decodedData = try decoder.decode(T.self, from: data)
return decodedData
} catch {
print(error)
return nil
}
}
}
Delegate in my VC:
override func viewDidLoad() {
super.viewDidLoad()
downloadManager.delegate = self
}
func didUpdateData(modelType: modelType,downloadedData:downloadedData){
DispatchQueue.main.async {
print(downloadedData)
}
}
To call download downloadRequest:
downloadManager.downloadrequest(modeType: Type1.self, parameters: parameters)
The Data Model is defined as a struct:
struct DataModel1: Codable {
let ItemID: String
}
Then in the same VC I call the same function downloadManager that will call a different API which should return data for a different Model Type (defined as Struct)
downloadManager.downloadRequest(modeType: Type2.self, parameters: parameters)
The Data Model is defined as a struct:
struct DataModel2: Codable {
let EmployeeeID: String
}
In the Swift times Protocol/Delegate smells a bit objective-c-ish.
I recommend a completion handler with the versatile Result type.
It returns the generic type non-optional on success and any error on failure.
The force unwrapping of data is safe because if error is nil then data has a value
struct DownloadManager {
func downloadRequest<T: Decodable>(modelType: T.Type, parameters: [String: Any], completion : #escaping (Result<T, Error>) -> Void) {
guard let url = URL(string: "https://www.someAPI...") else {return}
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
do {
let httpBodyWithParameters = try JSONSerialization.data(withJSONObject: parameters)
request.httpBody = httpBodyWithParameters
let session = URLSession.shared
session.dataTask(with: request) { (data, response, error) in
if let error = error {
completion(.failure(error))
} else {
completion( Result { try JSONDecoder().decode(T.self, from: data!)})
}
}.resume()
} catch {
completion(.failure(error))
}
}
}
And use it
downloadManager.downloadrequest(modeType: Type1.self, parameters: parameters) { result in
switch result {
case .success(let data): print(data)
case .failure(let error): print(error)
}
}
I am using this code to fetch data from an API and setting some variables in my view controller and everything works fine. Since I am doing this in multiple controllers I am attempting to refactor the network call into a Service class using a completion handler to execute the necessary code for settings the view's variables. The service works fine on some of the controllers, but any controller that attempts to decode an array of objects, I get the error
typeMismatch(Swift.Array, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Array but found a dictionary instead.", underlyingError: nil))
Working
let httpURL = "https://myurl.com/api"
guard let url = URL(string: httpURL) else { return }
var request = URLRequest(url: url)
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
// Setting other headers here
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
guard let data = data else {return}
do {
let consults = try JSONDecoder().decode([Consultation].self, from:data)
DispatchQueue.main.async {
// Settings values here
self.consultationTableView.reloadData()
}
} catch let jsonErr {
print(jsonErr)
}
}
task.resume()
}
Not Working
struct Service {
static let sharedInstance = Service()
func fetchPage(url: String, completion: #escaping (Data) -> ()){
let httpURL = "https://myurl.com/api"
guard let url = URL(string: httpURL) else { return }
var request = URLRequest(url: url)
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
// Other headers here
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
guard let data = data else {return}
completion(data)
}
task.resume()
}
}
ViewController
let httpURL = "https://myUrl.com/api"
Service.sharedInstance.fetchPage(url: httpURL) { (data) in
do {
let consults = try
---> Error Happens>> JSONDecoder().decode([Consultation].self, from:data) }
} catch let jsonErr {
print(jsonErr)
}
}
Any idea why when using the service class, the error shows up?