Basics of swift ios URLSession GET POST request . First we will check the basic and simple way to doing get post request using URLSession. Then we will check much cleaner way for callign api request in real life application
- swift 5
- URLSession
- JsonSerialization
- Encodable / Decodable
- URLComponents
- Generics
- Closures
- Simple get request using urlsession
- Simple post request
- Cleaner way for networking using Encodable & Decodable and Generics & Closures
- Passing query parameters
- Pass query parameter dynamically
- Download file with pause resume cancel
func getData() {
let url = URL(string: "PASTE YOUR GET URL HERE")
URLSession.shared.dataTask(with: url!) { (data, response, error) in
if error == nil {
if let data = data {
do {
if let jsonData = try JSONSerialization.jsonObject(with: data, options: []) as? Dictionary<String, Any> {
print(jsonData["NAME_OF_THE_KEY"])
}
} catch let err {
print(err)
}
}
}
}
}func postData() {
let url = URL(string: "PASTE YOUR POST URL HERE")
var urlRequest = URLRequest(url: url!)
let body = ["key": "value", "key": true, "key": 1] as [String : Any]
do {
urlRequest.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])
} catch let err {
print("err \(err)")
}
urlRequest.addValue("application/json", forHTTPHeaderField: "content-type")
urlRequest.httpMethod = "post"
URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
}
}struct SampleResponse: Decodable
{
let userName, email, phone: String
enum CodingKeys: String, CodingKey {
case userName = "user_name"
case email
case phone
}
}
struct SamplePostBody: Encodable {
let username, password: String
enum CodingKeys: String, CodingKey {
case username = "username"
case password = "password"
}
}Creating a APIService which will be used for calling api using urlsession. We can call get post request using this simple service from anywhere
struct APIService {
func requestService<T:Decodable>(urlRequest: URLRequest, resultType: T.Type, completionHandler: @escaping (_ result: T?,_ error: Error?) -> Void) {
URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
if error == nil {
if let data = data {
do {
let jsonData = try JSONDecoder().decode(T.self, from: data)
completionHandler(jsonData, nil)
} catch let err {
print(err)
completionHandler(nil, err)
}
}
}else {
completionHandler(nil, error)
}
}
}
}In the ViewModel class we can create fucntion for our get post request
class ViewModel {
var apiService: APIService2
init(_apiService: APIService2) {
apiService = _apiService
}
func getData() {
let url = URL(string: "GET_URL")
var urlRequest = URLRequest(url: url!)
urlRequest.httpMethod = "get"
apiService.requestService(urlRequest: urlRequest, resultType: SampleResponse.self) { (response, error) in
if error == nil {
print(response)
}
}
}
func postData() {
let url = URL(string: "POST_URL")
var urlRequest = URLRequest(url: url!)
urlRequest.httpMethod = "post"
let body = SamplePostBody(username: "username", password: "password")
do {
let postBody = try JSONEncoder().encode(body)
urlRequest.httpBody = postBody
urlRequest.addValue("application/json", forHTTPHeaderField: "content-type")
urlRequest.addValue("Authorization", forHTTPHeaderField: "TOKEN")
} catch let err {
print(err)
}
apiService.requestService(urlRequest: urlRequest, resultType: SampleResponse.self) { (response, error) in
}
}
}func queryParameterInUrlExample(color: String, model: String) {
let url = URL(string: "https://dummyurl.com/api/details?color=\(color)&model=\(model)")
// insted of passing in url we can use this
let urlWithooutQueryParameter = URL(string: "https://dummyurl.com/api/details")
var queryParameterURl = URLComponents(url: urlWithooutQueryParameter!, resolvingAgainstBaseURL: false)
queryParameterURl?.queryItems = [
URLQueryItem(name: "color", value: color),
URLQueryItem(name: "model", value: model)
]
var urlRequest = URLRequest(url: (queryParameterURl?.url)!)
}struct QueryPatameterItem: Encodable {
let color, model: String?
}
extension Encodable {
func convertToQueryParameter() -> [URLQueryItem]? {
do {
let encode = try JSONEncoder().encode(self)
let jsonDictionary = (try? JSONSerialization.jsonObject(with: encode, options: [])).flatMap{
$0 as? [String: Any?]
}
if jsonDictionary != nil {
var queryItems = [URLQueryItem]()
jsonDictionary?.forEach({ (key, value) in
if value != nil {
if let strValue = value as? String {
queryItems.append(URLQueryItem(name: key, value: strValue))
}
}
})
return queryItems
}
} catch let err {
print(err)
}
return nil
}
}
func queryParameterAdvanced(color: String, model: String) {
let urlWithooutQueryParameter = URL(string: "https://dummyurl.com/api/details")
var queryParameterURl = URLComponents(url: urlWithooutQueryParameter!, resolvingAgainstBaseURL: false)
let queryitems = QueryPatameterItem(color: "color", model: nil)
queryParameterURl?.queryItems = queryitems.convertToQueryParameter()
var urlRequest = URLRequest(url: (queryParameterURl?.url)!)
}protocol SongDownloadDelegate {
func downloadPercentage(parcentage: Float)
func downloadState(state: DownloadState)
}
enum DownloadState {
case waiting
case downloading
case pause
case finished
case canceled
}
class SongDownload: NSObject {
var downloadTask: URLSessionDownloadTask?
var downloadURL: URL?
var downloadLocation: URL?
var resumeData: Data?
var delegate: SongDownloadDelegate?
lazy var urlSession: URLSession = {
let confirguration = URLSessionConfiguration.default
return URLSession(configuration: confirguration, delegate: self, delegateQueue: nil)
}()
func getSongAtUrl(_ item: URL) {
downloadURL = item
downloadTask = urlSession.downloadTask(with: item)
downloadTask?.resume()
delegate?.downloadState(state: .downloading)
}
func cancel() {
downloadTask?.cancel()
delegate?.downloadState(state: .canceled)
}
func pause() {
downloadTask?.cancel(byProducingResumeData: { (data) in
DispatchQueue.main.async {
self.resumeData = data
self.delegate?.downloadState(state: .pause)
}
})
}
func resume() {
guard let resumeData = resumeData else {
return
}
downloadTask = self.urlSession.downloadTask(withResumeData: resumeData)
downloadTask?.resume()
delegate?.downloadState(state: .downloading)
}
}
extension SongDownload: URLSessionDownloadDelegate {
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
DispatchQueue.main.async {
self.delegate?.downloadPercentage(parcentage: Float(totalBytesWritten) / Float(totalBytesExpectedToWrite))
}
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
let fileManager = FileManager.default
guard let documentsPath = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first,
let lastPathComponent = downloadURL?.lastPathComponent else {
fatalError()
}
let destinationUrl = documentsPath.appendingPathComponent(lastPathComponent)
do{
if fileManager.fileExists(atPath: destinationUrl.path) {
try fileManager.removeItem(at: destinationUrl)
}
try fileManager.copyItem(at: location, to: destinationUrl)
DispatchQueue.main.async {
self.delegate?.downloadState(state: .finished)
self.downloadLocation = destinationUrl
}
}catch{
print(error)
}
}
}