Convert array to JSON string in swift

Question

How do you convert an array to a JSON string in swift  Basically I have a textfield with a button embedded in it  When button is pressed  the textfield text is added unto the testArray  Furthermore  I want to convert this array to a JSON string   This is what I have tried   func addButtonPressed         if goalsTextField text                    Do nothing       else           testArray append goalsTextField text          goalsTableView reloadData           saveDatatoDictionary            func saveDatatoDictionary         data   NSKeyedArchiver archivedDataWithRootObject testArray      newData   NSJSONSerialization JSONObjectWithData data   options  NSJSONReadingOptions    error  nil  as  NSData     string   NSString data  newData   encoding  NSUTF8StringEncoding       println string      I would also like to return the JSON string using my savetoDictionart   method

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For Swift 3 0 you have to use this   var postString          do           let data    try JSONSerialization data withJSONObject  self arrayNParcel  options   prettyPrinted          let string1 String   NSString data  data  encoding  String Encoding utf8 rawValue  as  String          postString    arrayData   string1  amp user id   userId  amp markupSrcReport   markup         catch           print error localizedDescription            request httpBody   postString data using   utf8    100  working TESTED

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As it stands you re converting it to data  then attempting to convert the data to to an object as JSON  which fails  it s not JSON  and converting that to a string  basically you have a bunch of meaningless transformations   As long as the array contains only JSON encodable values  string  number  dictionary  array  nil  you can just use NSJSONSerialization to do it   Instead just do the array- data- string parts   Swift 3 4  let array      one    two     func json from object Any  - gt  String        guard let data   try  JSONSerialization data withJSONObject  object  options      else           return nil           return String data  data  encoding  String Encoding utf8     print    json from array as Any       Original Answer  let array      one    two    let data   NSJSONSerialization dataWithJSONObject array  options  nil  error  nil  let string   NSString data  data   encoding  NSUTF8StringEncoding    although you should probably not use forced unwrapping  it gives you the right starting point

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How to convert array to json String in swift 2 3  var yourString   String      do       if let postData   NSData   try NSJSONSerialization dataWithJSONObject yourArray  options  NSJSONWritingOptions PrettyPrinted                yourString   NSString data  postData  encoding  NSUTF8StringEncoding   as String         catch       print error      And now you can use yourSting as JSON string

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Hint  To convert an NSArray containing JSON compatible objects to an NSData object containing a JSON document  use the appropriate method of NSJSONSerialization  JSONObjectWithData is not it    Hint 2  You rarely want that data as a string  only for debugging purposes

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SWIFT 2 0  var tempJson   NSString      do       let arrJson   try NSJSONSerialization dataWithJSONObject arrInvitationList  options  NSJSONWritingOptions PrettyPrinted      let string   NSString data  arrJson  encoding  NSUTF8StringEncoding      tempJson   string  as NSString  catch let error as NSError      print error description      NOTE - use tempJson variable when you want to use

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Swift 5 Make sure your object confirm Codable  Swift s default variable types like Int  String  Double and      all are Codable that means we can convert theme to Data and vice versa  For example  let s convert array of Int to String Base64 let array    1  2  3  let data   try  JSONEncoder   encode array  nsManagedObject array   data  base64EncodedString    Make sure your NSManaged variable type is String in core data schema editor and custom class if your using custom class for core data objects  let s convert back base64 string to array  var getArray   Int        guard let array   array else   return          guard let data   Data base64Encoded  array  else   return          guard let val   try  JSONDecoder   decode  Int  self  from  data  else   return          return val    Do not convert your own object to Base64 and store as String in CoreData and vice versa because we have something that named Relation in CoreData  databases

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If you re already using SwiftyJSON   https   github com SwiftyJSON SwiftyJSON  You can do this      this works with dictionaries too let paramsDictionary          title    foo        description    bar    let paramsArray      one    two    let paramsJSON   JSON paramsArray  let paramsString   paramsJSON rawString encoding  NSUTF8StringEncoding  options  nil    SWIFT 3 UPDATE   let paramsJSON   JSON paramsArray   let paramsString   paramsJSON rawString String Encoding utf8  options  JSONSerialization WritingOptions prettyPrinted     JSON strings  which are good for transport  don t come up often because you can JSON encode an HTTP body   But one potential use-case for JSON stringify is Multipart Post  which AlamoFire nows supports

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You can try this      func convertToJSONString value  AnyObject  - gt  String            if JSONSerialization isValidJSONObject value                do                  let data   try JSONSerialization data withJSONObject  value  options                      if let string   NSString data  data  encoding  String Encoding utf8 rawValue                        return string as String                                catch                                  return nil

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Swift 3 0 - 4 0 version  do          Convert to Data     let jsonData   try JSONSerialization data withJSONObject  dictionaryOrArray  options  JSONSerialization WritingOptions prettyPrinted         Convert back to string  Usually only do this for debugging     if let JSONString   String data  jsonData  encoding  String Encoding utf8           print JSONString               In production  you usually want to try and cast as the root data structure  Here we are casting as a dictionary  If the root object is an array cast as  Any       var json   try JSONSerialization jsonObject with  jsonData  options  JSONSerialization ReadingOptions mutableContainers  as   String  Any      catch       print error description      The JSONSerialization WritingOptions prettyPrinted option gives it to the eventual consumer in an easier to read format if they were to print it out in the debugger   Reference  Apple Documentation   The JSONSerialization ReadingOptions mutableContainers option lets you mutate the returned array s and or dictionaries    Reference for all ReadingOptions  Apple Documentation  NOTE  Swift 4 has the ability to encode and decode your objects using a new protocol  Here is Apples Documentation  and a quick tutorial for a starting example

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extension Array where Element  Encodable       func asArrayDictionary   throws - gt    String  Any             var data    String  Any                 for element in self               data append try element asDictionary                      return data          extension Encodable           func asDictionary   throws - gt   String  Any                let data   try JSONEncoder   encode self              guard let dictionary   try JSONSerialization jsonObject with  data  options   allowFragments  as   String  Any  else                   throw NSError                             return dictionary               If you re using Codable protocols in your models these extensions might be helpful for getting dictionary representation  Swift 4

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For Swift 4 2  that code still works fine   var mnemonic   String       abandon      amount      liar    buyer       var myJsonString          do           let data    try JSONSerialization data withJSONObject mnemonic  options   prettyPrinted         myJsonString   NSString data  data  encoding  String Encoding utf8 rawValue  as  String       catch           print error localizedDescription            return myJsonString

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