How to parse a JSON file in swift

Question

I have a JSON file  want to parse and use list of objects in table view  Can any one share the code to parse JSON file in swift

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This answer was last revised for Swift 5 3 and iOS 14 4 SDK   Given some already obtained JSON data  you can use JSONDecoder to decode it into your Decodable model  or a collection of models   let data  Data      obtain your JSON data    let model   try JSONDecoder   decode Model self  from  data   Such model must conform to the Decodable protocol and contain correct mapping between properties and JSON dictionary keys  As an example  consider the following JSON array containing search results of cities beginning with  quot Wa quot                    quot id quot   123           quot city quot    quot Washington quot            quot region quot    quot D C  quot            quot country quot    quot United States quot                        quot id quot   456           quot city quot    quot Warsaw quot            quot region quot    quot Mazowieckie quot            quot country quot    quot Poland quot                    For that  you need to create a model that contains the correct properties of correct types  If you re using a web API  its documentation will be of great help here  struct SearchResult  Decodable       let id  Int     let city  String     let region  String     let country  String    Then decode the data with JSONDecoder  let results   try JSONDecoder   decode  SearchResult  self  from  data   Given a new array of decoded search results  call one of UITableView s functions to reload its data  Note that the decode function can throw an error which you must somehow handle  To learn more about decoding custom types in Swift and more advanced usage of the Codable APIs  I recommend checking out this documentation article

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Install Swifty Json   Note  if you are looking for this  there s also a high chance you don t know how to install swifty  Follow the instructions here   sudo gem install cocoapods  cd   Path To Folder Containing ShowTracker   Next enter this command   pod init   This will create a default Podfile for your project  The Podfile is where you define the dependencies your project relies on   Type this command to open Podfile using Xcode for editing   open -a Xcode Podfile   Add the Swifty into the podfile  platform  ios   8 0  use frameworks   target  MyApp  do     pod  SwiftyJSON      gt  X X X  end    Check this example   var mURL   NSURL string   http   api openweathermap org data 2 5 weather q London uk amp units metric    if mURL    nil      println  You are stupid       return    var request   NSURLRequest URL  mURL    NSURLConnection sendAsynchronousRequest      request      queue  NSOperationQueue mainQueue        completionHandler             response  NSURLResponse            data  NSData            error  NSError   - gt  Void in      if data    nil            var mJSON   JSON data  data            if let current conditions   mJSON  weather   0   description   string               println  Current conditions      current conditions            else               println  MORON                       if let current temperature   mJSON  main    temp   double               println  Temperature     String format    f   current temperature        C            else               println  MORON

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This parser uses generics to cast JSON to Swift types which reduces the code you need to type   https   github com evgenyneu JsonSwiftson  struct Person     let name  String    let age  Int     let mapper   JsonSwiftson json       name      Peter      age    41      let person  Person    Person    name  mapper  name   map      age  mapper  age   map

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Codable  In Swift 4  is strongly recommended to use Codable instead of JSONSerialization    This Codable includes two protocols  Decodable and Encodable  This Decodable protocol allows you to decode Data in JSON format to custom struct class conforming to this protocol   For example imagine situation that we have this simple Data  array of two objects   let data   Data             name   Steve   age  56          name   iPhone   age  11        utf8    then have following struct and implement protocol Decodable  struct Person  Decodable       let name  String     let age  Int     now you can decode your Data to your array of Person using JSONDecoder where first parameter is type conforming to Decodable and to this type should Data be decoded  do       let people   try JSONDecoder   decode  Person  self  from  data    catch   print error          note that decoding has to be marked with try keyword since you could for example make some mistake with naming and then your model can t be decoded correctly     so you should put it inside do-try-catch block    Cases that key in json is different from name of property    If key is in named using snake case  you can set decoder s keyDecodingStrategy to convertFromSnakeCase which changes key from property name to camelCase propertyName  let decoder   JSONDecoder   decoder keyDecodingStrategy    convertFromSnakeCase let people   try decoder decode  Person  self  from  data   If you need unique name you can use coding keys inside struct class where you declare name of key  let data   Data         userName   Codable    age   1        utf8   struct Person  Decodable        let name  String     let age  Int      enum CodingKeys  String  CodingKey           case name    userName          case age

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Below is a Swift Playground example   import UIKit  let jsonString       name      John Doe      phone   123456    let data   jsonString data using   utf8   var jsonObject  Any do       jsonObject   try JSONSerialization jsonObject with  data   as Any      if let obj   jsonObject as  NSDictionary           print obj  name            catch       print  error

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Here is a code to make the conversions between JSON and NSData in Swift 2 0     Convert from NSData to json object func nsdataToJSON data  NSData  - gt  AnyObject        do           return try NSJSONSerialization JSONObjectWithData data  options   MutableContainers        catch let myJSONError           print myJSONError            return nil       Convert from JSON to nsdata func jsonToNSData json  AnyObject  - gt  NSData       do           return try NSJSONSerialization dataWithJSONObject json  options  NSJSONWritingOptions PrettyPrinted        catch let myJSONError           print myJSONError            return nil

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Parsing JSON in Swift is an excellent job for code generation   I ve created a tool at http   www guideluxe com JsonToSwift to do just that   You supply a sample JSON object with a class name and the tool will generate a corresponding Swift class  as well as any needed subsidiary Swift classes  to represent the structure implied by the sample JSON   Also included are class methods used to populate Swift objects  including one that utilizes the NSJSONSerialization JSONObjectWithData method  The necessary mappings from the NSArray and NSDictionary objects are provided   From the generated code  you only need to supply an NSData object containing JSON that matches the sample provided to the tool   Other than Foundation  there are no dependencies   My work was inspired by http   json2csharp com   which is very handy for  NET projects   Here s how to create an NSData object from a JSON file   let fileUrl  NSURL   NSBundle mainBundle   URLForResource  JsonFile   withExtension   json    let jsonData  NSData   NSData contentsOfURL  fileUrl

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Making the API Request  var request  NSURLRequest   NSURLRequest URL  url  var connection  NSURLConnection   NSURLConnection request  request  delegate  self  startImmediately  false    Preparing for the response  Declare an array as below  var data  NSMutableData   NSMutableData     Receiving the response  1   func connection didReceiveResponse  NSURLConnection   didReceiveResponse response  NSURLResponse           Received a new request  clear out the data object    self data   NSMutableData       2   func connection connection  NSURLConnection   didReceiveData data  NSData           Append the received chunk of data to our data object    self data appendData data      3   func connectionDidFinishLoading connection  NSURLConnection           Request complete  self data should now hold the resulting info       Convert the retrieved data in to an object through JSON deserialization    var err  NSError    var jsonResult  NSDictionary   NSJSONSerialization JSONObjectWithData data  options  NSJSONReadingOptions MutableContainers  error  nil  as NSDictionary     if jsonResult count gt 0  amp  amp  jsonResult  results   count gt 0         var results  NSArray   jsonResult  results   as NSArray       self tableData   results       self appsTableView reloadData             When NSURLConnection receives a response  we can expect the didReceiveResponse method to be called on our behalf  At this point we simply reset our data by saying self data   NSMutableData    creating a new empty data object   After a connection is made  we will start receiving data in the method didReceiveData  The data argument being passed in here is where all our juicy information comes from  We need to hold on to each chunk that comes in  so we append it to the self data object we cleared out earlier   Finally  when the connection is done and all data has been received  connectionDidFinishLoading is called and we   re ready to use the data in our app  Hooray   The connectionDidFinishLoading method here uses the NSJSONSerialization class to convert our raw data in to useful Dictionary objects by deserializing the results from your Url

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Swift 4 API Request Example  Make use of JSONDecoder   decode  See this video JSON parsing with Swift 4    struct Post  Codable       let userId  Int     let id  Int     let title  String     let body  String       URLSession shared dataTask with  URL string   https   jsonplaceholder typicode com posts        data  response  error  in      guard let response   response as  HTTPURLResponse else           print  HTTPURLResponse error           return            guard 200     299    response statusCode else           print  Status Code error   response statusCode            return            guard let data   data else           print  No Data           return            let posts   try  JSONDecoder   decode  Post  self  from  data      print posts          resume

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SwiftJSONParse  Parse JSON like a badass  Dead-simple and easy to read   Example  get the value  mrap  from nicknames as a String from this JSON response         other              nicknames     mrap    Mikee       It takes your json data NSData as it is  no need to preprocess   let parser   JSONParser jsonData   if let handle   parser getString  other nicknames 0             that s it      Disclaimer  I made this and I hope it helps everyone  Feel free to improve on it

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Swift 3  let parsedResult   String  AnyObject  do             parsedResult   try JSONSerialization jsonObject with  data  options   allowFragments  as   String AnyObject           catch                  Display an error or return or whatever     data - it s Data type  Structure    i e  returned by some server response

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I just wrote a class called JSON  which makes JSON handling in Swift as easy as JSON object in ES5    https   github com dankogai swift-json    Turn your swift object to JSON like so   let obj  String AnyObject           array    JSON null  false  0                   object             null     JSON null           bool     true           int      42           double   3 141592653589793           string    a a t  n            array                 object                   url   http   blog livedoor com dankogai      let json   JSON obj  json toString        or string     let json   JSON parse     array                or URL   let json   JSON fromURL  http   api dan co jp jsonenv   Tree Traversal   Just traverse elements via subscript   json  object    null   asNull          NSNull          json  object    string   asString       a a t  n  json  array   0  asNull                NSNull   json  array   1  asBool                false          Just like SwiftyJSON you don t worry if the subscripted entry does not exist   if let b   json  noexistent   1234567890   entry   asBool                 else       let e   json  noexistent   1234567890   entry   asError     println e      If you are tired of subscripts  add your scheme like so        schema by subclassing class MyJSON   JSON       init   obj AnyObject   super init obj        init   json JSON     super init json        var null   NSNull    return self  null   asNull       var bool   Bool      return self  bool   asBool       var int    Int       return self  int   asInt       var double Double    return self  double   asDouble       var string String    return self  string   asString       And you go   let myjson   MyJSON obj  myjson object null myjson object bool myjson object int myjson object double myjson object string          Hope you like it   With the new xCode 7 3  its important to add your domain to the exception list  How can I add NSAppTransportSecurity to my info plist file    refer to this posting for instructions  otherwise you will get a transport authority error

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I also wrote a small library which is specialized for the mapping of the json response into an object structure  I am internally using the library json-swift from David Owens  Maybe it is useful for someone else   https   github com prine ROJSONParser  Example Employees json     employees              firstName    John        lastName    Doe        age   26               firstName    Anna        lastName    Smith        age   30               firstName    Peter        lastName    Jones        age   45          As next step you have to create your data model  EmplyoeeContainer and Employee    Employee swift  class Employee   ROJSONObject        required init             super init               required init jsonData AnyObject            super init jsonData  jsonData             var firstname String           return Value lt String gt  get self  key   firstName              var lastname String           return Value lt String gt  get self  key   lastName                          var age Int           return Value lt Int gt  get self  key   age             EmployeeContainer swift  class EmployeeContainer   ROJSONObject       required init             super init               required init jsonData AnyObject            super init jsonData  jsonData             lazy var employees  Employee              return Value lt  Employee  gt  getArray self  key   employees   as  Employee              Then to actually map the objects from the JSON response you only have to pass the data into the EmployeeContainer class as param in the constructor  It does automatically create your data model    var baseWebservice BaseWebservice   BaseWebservice       var urlToJSON    http   prine ch employees json     var callbackJSON     status Int  employeeContainer EmployeeContainer  - gt     in     for employee in employeeContainer employees         println  Firstname    employee firstname  Lastname    employee lastname  age    employee age                 baseWebservice get urlToJSON  callback callbackJSON    The console output looks then like the following   Firstname  John Lastname  Doe age  26 Firstname  Anna Lastname  Smith age  30 Firstname  Peter Lastname  Jones age  45

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The entire viewcontroller which show data in collecction view using two methods of json parsig   IBOutlet weak var imagecollectionview  UICollectionView  lazy var data   NSMutableData   var dictdata   NSMutableDictionary   NSMutableDictionary   override func viewDidLoad         super viewDidLoad       startConnection       startNewConnection          Do any additional setup after loading the view  typically from a nib      func collectionView collectionView  UICollectionView  numberOfItemsInSection section  Int  - gt  Int       return dictdata count   func collectionView collectionView  UICollectionView  cellForItemAtIndexPath indexPath  NSIndexPath  - gt  UICollectionViewCell        let cell    collectionView dequeueReusableCellWithReuseIdentifier  CustomcellCollectionViewCell   forIndexPath  indexPath  as  CustomcellCollectionViewCell     cell name text   dictdata valueForKey  Data    valueForKey  location   as  String     let url   NSURL string   dictdata valueForKey  Data    valueForKey  avatar url   as  String          LazyImage showForImageView cell image  url  URL     return cell   func collectionView collectionView  UICollectionView                      layout collectionViewLayout  UICollectionViewLayout                             sizeForItemAtIndexPath indexPath  NSIndexPath  - gt  CGSize       let kWhateverHeightYouWant   100     return CGSizeMake self view bounds size width 2  CGFloat kWhateverHeightYouWant      func startNewConnection         let url  URL   URL string   YOUR URL  as String       let session   URLSession shared      let request   NSMutableURLRequest url  url as URL      request httpMethod    GET    set the get or post according to your request                request cachePolicy   NSURLRequest CachePolicy ReloadIgnoringCacheData     request cachePolicy   NSURLRequest CachePolicy reloadIgnoringCacheData      let task   session dataTask with  request as URLRequest              data  response  error  in          guard let   NSData   data as NSData   let   URLResponse   response  error    nil else               print  error               return                   let jsonString   NSString data  data   encoding String Encoding utf8 rawValue  as  String                      task resume       func startConnection        let urlPath  String    your URL      let url  NSURL   NSURL string  urlPath       var request  NSURLRequest   NSURLRequest URL  url      var connection  NSURLConnection   NSURLConnection request  request  delegate  self  startImmediately  false       connection start      func connection connection  NSURLConnection   didReceiveData data  NSData        self data appendData data     func buttonAction sender  UIButton        startConnection      func connectionDidFinishLoading connection  NSURLConnection         do           let JSON   try NSJSONSerialization JSONObjectWithData self data  options NSJSONReadingOptions rawValue  0           guard let JSONDictionary  NSDictionary   JSON as  NSDictionary else               print  Not a Dictionary                  put in function             return                   print  JSONDictionary    JSONDictionary            dictdata setObject JSONDictionary  forKey   Data            imagecollectionview reloadData             catch let JSONError as NSError           print    JSONError

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Using ObjectMapper framework  if let path   Bundle for  BPPView self  path forResource  jsonFileName  ofType   json         do           let data   try Data contentsOf  URL fileURLWithPath  path   options  NSData ReadingOptions mappedIfSafe          let json   try JSONSerialization jsonObject with  data  options   allowFragments          self levels   Mapper lt Level gt    mapArray JSONArray   json as    String   Any              print levels count        catch let error as NSError           print error localizedDescription          else       print  Invalid filename path        Before you should prepare the set of appropriate  Mappable objects to parse into  import UIKit  import ObjectMapper class Level  Mappable   var levelName      var levelItems    LevelItem     required init  map  Map           Mappable func mapping map  Map        levelName  lt - map  levelName       levelItems  lt - map  levelItems          import UIKit  import ObjectMapper  class LevelItem  Mappable   var frontBackSide   BPPFrontBack Undefined var fullImageName      var fullImageSelectedName      var bodyParts    BodyPart     required init  map  Map           Mappable func mapping map  Map        frontBackSide  lt - map  frontBackSide       fullImageName  lt - map  fullImageName       fullImageSelectedName  lt - map  fullImageSelectedName       bodyParts  lt - map  bodyParts

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Swift 4   Create a Project   Design StoryBoard With a Button and a UITableview  Create TableViewCell VC  In Button Action Insert the folloeing Codes  Remember This Code for Fetch Array of Data in an Api  import UIKit  class ViewController3  UIViewController UITableViewDelegate UITableViewDataSource         IBOutlet var tableView  UITableView      var displayDatasssss    displyDataClass        override func viewDidLoad             super viewDidLoad               Do any additional setup after loading the view            func numberOfSections in tableView  UITableView  - gt  Int           return 1           func tableView   tableView  UITableView  numberOfRowsInSection section  Int  - gt  Int           return displayDatasssss count           func tableView   tableView  UITableView  cellForRowAt indexPath  IndexPath  - gt  UITableViewCell           let cell   tableView dequeueReusableCell withIdentifier   TableViewCell1   as  TableViewCell1         cell label1 text   displayDatasssss indexPath row  email         return cell           override func didReceiveMemoryWarning             super didReceiveMemoryWarning              Dispose of any resources that can be recreated              IBAction func gettt   sender  Any             let url    http   jsonplaceholder typicode com users          var request   URLRequest url  URL string  url            request httpMethod    GET          let configuration   URLSessionConfiguration default         let session   URLSession configuration  configuration  delegate  nil  delegateQueue  OperationQueue main          let task   session dataTask with  request   data  response error in             if  error    nil                   print  Error                             else                  do                         Array of Data                      let fetchData   try JSONSerialization jsonObject with  data   options   mutableLeaves  as  NSArray                      for eachData in fetchData                            let eachdataitem   eachData as   String   Any                          let name   eachdataitem  name  as  String                         let username   eachdataitem  username  as  String                          let email   eachdataitem  email  as  String                          self displayDatasssss append displyDataClass name  name  username  username email   email                                             self tableView reloadData                                     catch                      print  Error 2                                                      task resume            class displyDataClass       var name   String     var username   String     var email   String      init name   String username   String email  String            self name   name         self username   username         self email   email           This is for Dictionary data Fetching  import UIKit  class ViewController3  UIViewController UITableViewDelegate UITableViewDataSource         IBOutlet var tableView  UITableView      var displayDatasssss    displyDataClass        override func viewDidLoad             super viewDidLoad               Do any additional setup after loading the view            func numberOfSections in tableView  UITableView  - gt  Int           return 1           func tableView   tableView  UITableView  numberOfRowsInSection section  Int  - gt  Int           return displayDatasssss count           func tableView   tableView  UITableView  cellForRowAt indexPath  IndexPath  - gt  UITableViewCell           let cell   tableView dequeueReusableCell withIdentifier   TableViewCell1   as  TableViewCell1         cell label1 text   displayDatasssss indexPath row  email         return cell           override func didReceiveMemoryWarning             super didReceiveMemoryWarning              Dispose of any resources that can be recreated              IBAction func gettt   sender  Any             let url    http   jsonplaceholder typicode com users 1          var request   URLRequest url  URL string  url            request httpMethod    GET          let configuration   URLSessionConfiguration default         let session   URLSession configuration  configuration  delegate  nil  delegateQueue  OperationQueue main          let task   session dataTask with  request   data  response error in             if  error    nil                   print  Error                             else                  do                        Dictionary data Fetching                     let fetchData   try JSONSerialization jsonObject with  data   options   mutableLeaves  as   String  AnyObject                          let name   fetchData  name  as  String                         let username   fetchData  username  as  String                          let email   fetchData  email  as  String                          self displayDatasssss append displyDataClass name  name  username  username email   email                        self tableView reloadData                                     catch                      print  Error 2                                                      task resume            class displyDataClass       var name   String     var username   String     var email   String      init name   String username   String email  String            self name   name         self username   username         self email   email

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Swift 2 iOS 9  let miadata   NSData contentsOfURL  NSURL string   https   myWeb    php      do      let MyData   try NSJSONSerialization JSONObjectWithData miadata   options  NSJSONReadingOptions MutableContainers  as  NSArray     print             MyData          catch let error as NSError         error description     print error description

[ios] How to parse a JSON file in swift?

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