How to generate JSON string in Swift 3? - ios

I am trying to send a request to an API that requires this format:
{
"inputs": [
{
"data": {
"image": {
"base64": "iVBORw0KGgoAAAIVnFT/DPAAAAAElFTkSuQmCC..."
}
}
}
]
}
This is what I tried in Swift 3:
let base64 = ["base64": "1010101..."]
let image: [String: Any] = ["image": base64]
let data: [String: Any] = ["data": image]
var input = [Dictionary<String, Any>]()
input = [data]
let jsonData = try! JSONSerialization.data(withJSONObject: input, options: .prettyPrinted)
I got an invalid request error when trying to hit the endpoint. Not surprising - when I printed it:
let jsonString = try! JSONSerialization.jsonObject(with: jsonData, options: [])
print(jsonString)
It produced a string like this:
(
{
data = {
image = {
base64 = 1010101;
};
};
}
)
For now, I am rolling my own string. It works...but it's ugly as hell and just really not tenable.
let imageAsString = "{\"inputs\": [{\"data\": {\"image\": {\"base64\": \"\(strBase64)\"}}}]}"
My other thought was that I could create a series of embedded objects: a Data object that holds a dictionary; an Image object that holds a Data object; and an Inputs object that holds an array of Data objects.
class Image {
var base64 = Dictionary<String, String>()
}
class Data {
var image = Image()
}
class Inputs {
var inputs = [Data]()
}
But initializing them all and calling JSONSerialization.data doesn't work as this takes a dictionary object.
I'm not really interested in pulling in 3rd party plugins for now. Any ideas on how to convert these nested objects into json using the native iOS libraries?

Absolutely! Using the Codable protocol and JSONEncoder in Swift 4 will do the trick:
struct ImageObj: Codable {
let base64: String
}
struct DataObj: Codable {
let image: ImageObj
}
struct InputObj: Codable {
let data: DataObj
}
struct InputsContainerObj: Codable {
let inputs: [InputObj]
}
let imageObj = ImageObj(base64: "abc123")
let dataObj = DataObj(image: imageObj)
let inputObj = InputObj(data: dataObj)
let inputsContainerObj = InputsContainerObj(inputs: [inputObj])
let encoder = JSONEncoder()
do {
let jsonData = try encoder.encode(inputsContainerObj)
let jsonString = String(data: jsonData, encoding: .utf8)!
print(jsonString) //{"inputs":[{"data":{"image":{"base64":"abc123"}}}]}
} catch _ as NSError {
}
If Swift 3 is your only option, then you will have to make JSONSerialization.data work:
let dict = ["inputs": [["data": ["image": ["base64": "abc123"]]]]]
do {
let jsonData = try JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)
let jsonString = String(data: jsonData, encoding: .utf8)!
print(jsonString)
/*
{
"inputs" : [
{
"data" : {
"image" : {
"base64" : "abc123"
}
}
}
]
}
*/
} catch _ as NSError {
}

Related

How to convert stored values to JSON format using Swift?

I am trying to convert stored coredata values to JSON format and the JSON format value need to assign a single variable, because this generated JSON I need to send to server. Below code I tried to get coredata stored values but don’t know how to generate JSON required format.
Getting values from coredata
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "User")
do {
let results = try context.fetch(fetchRequest)
let dateCreated = results as! [Userscore]
for _datecreated in dateCreated {
print("\(_datecreated.id!)-\(_datecreated.name!)") // Output: 79-b \n 80-c \n 78-a
}
} catch let err as NSError {
print(err.debugDescription)
}
Need to Convert Coredata Value to Below JSON format
{
    "status": true,
    "data": [
        {
            "id": "20",
            "name": "a"
        },
        {
            "id": "21",
            "name": "b"
        },
        {
            "id": "22",
            "name": "c"
        }
    ]
}
Probably the easiest is to convert your object(s) to either dictionaries or arrays (depending on what you need).
First you need to be able to convert your Userscore to dictionary. I will use extension on it since I have no idea what your entity looks like:
extension Userscore {
func toDictionary() -> [String: Any]? {
guard let id = id else { return nil }
guard let name = name else { return nil }
return [
"id": id,
"name": name
]
}
}
Now this method can be used to generate an array of your dictionaries simply using let arrayOfUserscores: [[String: Any]] = userscores.compactMap { $0.toDictionary() }.
Or to build up your whole JSON as posted in question:
func generateUserscoreJSON(userscores: [Userscore]) -> Data? {
var payload: [String: Any] = [String: Any]()
payload["status"] = true
payload["data"] = userscores.compactMap { $0.toDictionary() }
return try? JSONSerialization.data(withJSONObject: payload, options: .prettyPrinted)
}
This will now create raw data ready to be sent to server for instance
var request = URLRequest(url: myURL)
request.httpBody = generateUserscoreJSON(userscores: userscores)
You can use the properties of an Encodable to make this happen. This has the added benefit of not resorting to the Any type.
For the JSON, you could use the following types:
struct JSONMessage: Encodable {
var status: Bool
var data: [JSONDataEntry]
}
struct JSONDataEntry: Encodable {
var id: String
var name: String
}
Then you can adjust your do/try/catch as follows:
do {
let results = try context.fetch(fetchRequest)
let dateCreated = results as! [Userscore]
// *starting here*
let data = dateCreated.map { JSONDataEntry(id: String($0.id!), name: $0.name!) }
let status = true // <- not sure where status comes from, so adding here
let message = JSONMessage(status: status, data: data)
let jsonData = try JSONEncoder().encode(message)
if let json = String(data: jsonData, encoding: .utf8) {
// do something with the JSON string
print(json)
}
// *ending here*
} catch let err as NSError {
print(err.debugDescription)
}

How to send json data with json object in swift 4

I need to send json to server in following order
data:{"firstname":"Alpha","lastname":"Beta"}
In this the data key is outside of json like [data:json] but when I am serialization it making the request as
{
"data" : {
"firstname" : "alpha",
"lastname" : "beta"
}
}
These are my models :
struct UserDetail :Codable {
let data :CreateProfileModel
}
struct CreateProfileModel :Codable {
let firstname :String
let lastname :String
}
Data I am adding in these models
let profileInfo = CreateProfileModel(firstname: "alpha" , lastname: "beta")
let userDetails = UserDetail(data: profileInfo)
This is the json encoding that I am doing using swift :
let jsonEncoder = JSONEncoder()
jsonEncoder.outputFormatting = .prettyPrinted
do{
let userData = try jsonEncoder.encode(userDetails)
print(String(data: userData, encoding: .utf8)!)
networkListener.requestPost(endpoint: endpoint, data: userData , headerValue: nil)
}catch{
print(error)
}
In requestPost method
func requestPost(endpoint : String , data :Data,headerValue : String?){....
request.httpbody = data
}
I am adding that data the request.httpbody.
How can i add data key with profileInfo ?
Try this Code:
var columnValus:[String:Any] = [:]
columnValus["firstname"] = userDetails.data.firstname
columnValus["lastname"] = userDetails.data.lastname
let userData = [
"data": columnValus
] as [String : Any]
do {
let postData = try JSONSerialization.data(withJSONObject: userData, options: [])
networkListener.requestPost(endpoint: endpoint, data: postData , headerValue: nil)
}catch let error as NSError {
print(error)
}
If the API requires (effectively) HTML form data, you'll need to construct the body yourself and extract bits of JSON.
Try:
let userData = try jsonEncoder.encode(userDetails.data)
let postBodyString = "data:\(userData)"
let postBodyData = postBodyString.data(using: String.Encoding.utf8)
networkListener.requestPost(endpoint: endpoint, data: postBodyData, headerValue: nil)

Convert Json string to Json object in Swift 4

I try to convert JSON string to a JSON object but after JSONSerialization the output is nil in JSON.
Response String:
[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]
I try to convert this string with my code below:
let jsonString = response.result.value
let data: Data? = jsonString?.data(using: .utf8)
let json = (try? JSONSerialization.jsonObject(with: data, options: [])) as? [String:AnyObject]
print(json ?? "Empty Data")
The problem is that you thought your jsonString is a dictionary. It's not.
It's an array of dictionaries.
In raw json strings, arrays begin with [ and dictionaries begin with {.
I used your json string with below code :
let string = "[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]"
let data = string.data(using: .utf8)!
do {
if let jsonArray = try JSONSerialization.jsonObject(with: data, options : .allowFragments) as? [Dictionary<String,Any>]
{
print(jsonArray) // use the json here
} else {
print("bad json")
}
} catch let error as NSError {
print(error)
}
and I am getting the output :
[["form_desc": <null>, "form_name": Activity 4 with Images, "canonical_name": df_SAWERQ, "form_id": 3465]]
Using JSONSerialization always felt unSwifty and unwieldy, but it is even more so with the arrival of Codable in Swift 4. If you wield a [String:Any] in front of a simple struct it will ... hurt. Check out this in a Playground:
import Cocoa
let data = "[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]".data(using: .utf8)!
struct Form: Codable {
let id: Int
let name: String
let description: String?
private enum CodingKeys: String, CodingKey {
case id = "form_id"
case name = "form_name"
case description = "form_desc"
}
}
do {
let f = try JSONDecoder().decode([Form].self, from: data)
print(f)
print(f[0])
} catch {
print(error)
}
With minimal effort handling this will feel a whole lot more comfortable. And you are given a lot more information if your JSON does not parse properly.
I tried the solutions here, and as? [String:AnyObject] worked for me:
do{
if let json = stringToParse.data(using: String.Encoding.utf8){
if let jsonData = try JSONSerialization.jsonObject(with: json, options: .allowFragments) as? [String:AnyObject]{
let id = jsonData["id"] as! String
...
}
}
}catch {
print(error.localizedDescription)
}
I used below code and it's working fine for me. :
let jsonText = "{\"userName\":\"Bhavsang\"}"
var dictonary:NSDictionary?
if let data = jsonText.dataUsingEncoding(NSUTF8StringEncoding) {
do {
dictonary = try NSJSONSerialization.JSONObjectWithData(data, options: [.allowFragments]) as? [String:AnyObject]
if let myDictionary = dictonary
{
print(" User name is: \(myDictionary["userName"]!)")
}
} catch let error as NSError {
print(error)
}
}
static func getJSONStringFromObject(object: Any?) -> String? {
do {
let jsonData = try JSONSerialization.data(withJSONObject: object ?? DUMMY_STRING, options: [])
return String(data: jsonData, encoding: .utf8) ?? DUMMY_STRING
} catch {
print(error.localizedDescription)
}
return DUMMY_STRING
}

Return JSON on output Swift [duplicate]

I have create the next Dictionary:
var postJSON = [ids[0]:answersArray[0], ids[1]:answersArray[1], ids[2]:answersArray[2]] as Dictionary
and I get:
[2: B, 1: A, 3: C]
So, how can I convert it to JSON?
Swift 3.0
With Swift 3, the name of NSJSONSerialization and its methods have changed, according to the Swift API Design Guidelines.
let dic = ["2": "B", "1": "A", "3": "C"]
do {
let jsonData = try JSONSerialization.data(withJSONObject: dic, options: .prettyPrinted)
// here "jsonData" is the dictionary encoded in JSON data
let decoded = try JSONSerialization.jsonObject(with: jsonData, options: [])
// here "decoded" is of type `Any`, decoded from JSON data
// you can now cast it with the right type
if let dictFromJSON = decoded as? [String:String] {
// use dictFromJSON
}
} catch {
print(error.localizedDescription)
}
Swift 2.x
do {
let jsonData = try NSJSONSerialization.dataWithJSONObject(dic, options: NSJSONWritingOptions.PrettyPrinted)
// here "jsonData" is the dictionary encoded in JSON data
let decoded = try NSJSONSerialization.JSONObjectWithData(jsonData, options: [])
// here "decoded" is of type `AnyObject`, decoded from JSON data
// you can now cast it with the right type
if let dictFromJSON = decoded as? [String:String] {
// use dictFromJSON
}
} catch let error as NSError {
print(error)
}
Swift 1
var error: NSError?
if let jsonData = NSJSONSerialization.dataWithJSONObject(dic, options: NSJSONWritingOptions.PrettyPrinted, error: &error) {
if error != nil {
println(error)
} else {
// here "jsonData" is the dictionary encoded in JSON data
}
}
if let decoded = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: &error) as? [String:String] {
if error != nil {
println(error)
} else {
// here "decoded" is the dictionary decoded from JSON data
}
}
You are making a wrong assumption. Just because the debugger/Playground shows your dictionary in square brackets (which is how Cocoa displays dictionaries) that does not mean that is the way the JSON output is formatted.
Here is example code that will convert a dictionary of strings to JSON:
Swift 3 version:
import Foundation
let dictionary = ["aKey": "aValue", "anotherKey": "anotherValue"]
if let theJSONData = try? JSONSerialization.data(
withJSONObject: dictionary,
options: []) {
let theJSONText = String(data: theJSONData,
encoding: .ascii)
print("JSON string = \(theJSONText!)")
}
To display the above in "pretty printed" format you'd change the options line to:
options: [.prettyPrinted]
Or in Swift 2 syntax:
import Foundation
let dictionary = ["aKey": "aValue", "anotherKey": "anotherValue"]
let theJSONData = NSJSONSerialization.dataWithJSONObject(
dictionary ,
options: NSJSONWritingOptions(0),
error: nil)
let theJSONText = NSString(data: theJSONData!,
encoding: NSASCIIStringEncoding)
println("JSON string = \(theJSONText!)")
The output of that is
"JSON string = {"anotherKey":"anotherValue","aKey":"aValue"}"
Or in pretty format:
{
"anotherKey" : "anotherValue",
"aKey" : "aValue"
}
The dictionary is enclosed in curly braces in the JSON output, just as you'd expect.
EDIT:
In Swift 3/4 syntax, the code above looks like this:
let dictionary = ["aKey": "aValue", "anotherKey": "anotherValue"]
if let theJSONData = try? JSONSerialization.data(
withJSONObject: dictionary,
options: .prettyPrinted
),
let theJSONText = String(data: theJSONData,
encoding: String.Encoding.ascii) {
print("JSON string = \n\(theJSONText)")
}
}
Swift 5:
let dic = ["2": "B", "1": "A", "3": "C"]
let encoder = JSONEncoder()
if let jsonData = try? encoder.encode(dic) {
if let jsonString = String(data: jsonData, encoding: .utf8) {
print(jsonString)
}
}
Note that keys and values must implement Codable. Strings, Ints, and Doubles (and more) are already Codable. See Encoding and Decoding Custom Types.
Also note that Any does not conform to Codable. It is likely still a good approach to adapt your data to become Codable so that you are making use of Swift typing (especially in the case that you are also going to decode any encoded json), and so that you can be more declarative about the outcome of your encoding.
My answer for your question is below
let dict = ["0": "ArrayObjectOne", "1": "ArrayObjecttwo", "2": "ArrayObjectThree"]
var error : NSError?
let jsonData = try! NSJSONSerialization.dataWithJSONObject(dict, options: NSJSONWritingOptions.PrettyPrinted)
let jsonString = NSString(data: jsonData, encoding: String.Encoding.utf8.rawValue)! as String
print(jsonString)
Answer is
{
"0" : "ArrayObjectOne",
"1" : "ArrayObjecttwo",
"2" : "ArrayObjectThree"
}
Swift 4 Dictionary extension.
extension Dictionary {
var jsonStringRepresentation: String? {
guard let theJSONData = try? JSONSerialization.data(withJSONObject: self,
options: [.prettyPrinted]) else {
return nil
}
return String(data: theJSONData, encoding: .ascii)
}
}
Sometimes it's necessary to print out server's response for debugging purposes. Here's a function I use:
extension Dictionary {
var json: String {
let invalidJson = "Not a valid JSON"
do {
let jsonData = try JSONSerialization.data(withJSONObject: self, options: .prettyPrinted)
return String(bytes: jsonData, encoding: String.Encoding.utf8) ?? invalidJson
} catch {
return invalidJson
}
}
func printJson() {
print(json)
}
}
Example of use:
(lldb) po dictionary.printJson()
{
"InviteId" : 2,
"EventId" : 13591,
"Messages" : [
{
"SenderUserId" : 9514,
"MessageText" : "test",
"RecipientUserId" : 9470
},
{
"SenderUserId" : 9514,
"MessageText" : "test",
"RecipientUserId" : 9470
}
],
"TargetUserId" : 9470,
"InvitedUsers" : [
9470
],
"InvitingUserId" : 9514,
"WillGo" : true,
"DateCreated" : "2016-08-24 14:01:08 +00:00"
}
Swift 5:
extension Dictionary {
/// Convert Dictionary to JSON string
/// - Throws: exception if dictionary cannot be converted to JSON data or when data cannot be converted to UTF8 string
/// - Returns: JSON string
func toJson() throws -> String {
let data = try JSONSerialization.data(withJSONObject: self)
if let string = String(data: data, encoding: .utf8) {
return string
}
throw NSError(domain: "Dictionary", code: 1, userInfo: ["message": "Data cannot be converted to .utf8 string"])
}
}
Swift 3:
let jsonData = try? JSONSerialization.data(withJSONObject: dict, options: [])
let jsonString = String(data: jsonData!, encoding: .utf8)!
print(jsonString)
In Swift 5.4
extension Dictionary {
var jsonData: Data? {
return try? JSONSerialization.data(withJSONObject: self, options: [.prettyPrinted])
}
func toJSONString() -> String? {
if let jsonData = jsonData {
let jsonString = String(data: jsonData, encoding: .utf8)
return jsonString
}
return nil
}
}
The idea of having it as a variable is because then you can reuse it like that:
extension Dictionary {
func decode<T:Codable>() throws -> T {
return try JSONDecoder().decode(T.self, from: jsonData ?? Data())
}
}
Answer for your question is below:
Swift 2.1
do {
if let postData : NSData = try NSJSONSerialization.dataWithJSONObject(dictDataToBeConverted, options: NSJSONWritingOptions.PrettyPrinted){
let json = NSString(data: postData, encoding: NSUTF8StringEncoding)! as String
print(json)}
}
catch {
print(error)
}
Here's an easy extension to do this:
https://gist.github.com/stevenojo/0cb8afcba721838b8dcb115b846727c3
extension Dictionary {
func jsonString() -> NSString? {
let jsonData = try? JSONSerialization.data(withJSONObject: self, options: [])
guard jsonData != nil else {return nil}
let jsonString = String(data: jsonData!, encoding: .utf8)
guard jsonString != nil else {return nil}
return jsonString! as NSString
}
}
using lldb
(lldb) p JSONSerialization.data(withJSONObject: notification.request.content.userInfo, options: [])
(Data) $R16 = 375 bytes
(lldb) p String(data: $R16!, encoding: .utf8)!
(String) $R18 = "{\"aps\": \"some_text\"}"
//or
p String(data: JSONSerialization.data(withJSONObject: notification.request.content.userInfo, options: [])!, encoding: .utf8)!
(String) $R4 = "{\"aps\": \"some_text\"}"
do{
let dataDict = [ "level" :
[
["column" : 0,"down" : 0,"left" : 0,"right" : 0,"row" : 0,"up" : 0],
["column" : 1,"down" : 0,"left" : 0,"right" : 0,"row" : 0,"up" : 0],
["column" : 2,"down" : 0,"left" : 0,"right" : 0,"row" : 0,"up" : 0],
["column" : 0,"down" : 0,"left" : 0,"right" : 0,"row" : 1,"up" : 0],
["column" : 1,"down" : 0,"left" : 0,"right" : 0,"row" : 1,"up" : 0],
["column" : 2,"down" : 0,"left" : 0,"right" : 0,"row" : 1,"up" : 0]
]
]
var jsonData = try JSONSerialization.data(withJSONObject: dataDict, options: JSONSerialization.WritingOptions.prettyPrinted)
let jsonStringData = NSString(data: jsonData as Data, encoding: NSUTF8StringEncoding)! as String
print(jsonStringData)
}catch{
print(error.localizedDescription)
}
This works for me:
import SwiftyJSON
extension JSON {
mutating func appendIfKeyValuePair(key: String, value: Any){
if var dict = self.dictionaryObject {
dict[key] = value
self = JSON(dict)
}
}
}
Usage:
var data: JSON = []
data.appendIfKeyValuePair(key: "myKey", value: "myValue")
2022, swift 5
usage of extensions:
Encode:
if let json = statisticsDict.asJSONStr() {
//your action with json
}
Decode from Dictionary:
json.decodeFromJson(type: [String:AppStat].self)
.onSuccess{
$0// your dictionary of type: [String:AppStat]
}
extensions:
extension Dictionary where Key: Encodable, Value: Encodable {
func asJSONStr() -> String? {
let encoder = JSONEncoder()
if let jsonData = try? encoder.encode(self) {
if let jsonString = String(data: jsonData, encoding: .utf8) {
return jsonString
}
}
return nil
}
}
public extension String {
func decodeFromJson<T>(type: T.Type) -> Result<T, Error> where T: Decodable {
self.asData()
.flatMap { JSONDecoder().try(type, from: $0) }
}
func asData() -> Result<Data, Error> {
if let data = self.data(using: .utf8) {
return .success(data)
} else {
return .failure(WTF("can't convert string to data: \(self)"))
}
}
}
extension JSONDecoder {
func `try`<T: Decodable>(_ t: T.Type, from data: Data) -> Result<T,Error> {
do {
return .success(try self.decode(t, from: data))
} catch {
return .failure(error)
}
}
}
private func convertDictToJson(dict : NSDictionary) -> NSDictionary?
{
var jsonDict : NSDictionary!
do {
let jsonData = try JSONSerialization.data(withJSONObject:dict, options:[])
let jsonDataString = String(data: jsonData, encoding: String.Encoding.utf8)!
print("Post Request Params : \(jsonDataString)")
jsonDict = [ParameterKey : jsonDataString]
return jsonDict
} catch {
print("JSON serialization failed: \(error)")
jsonDict = nil
}
return jsonDict
}

Convert array to JSON string in swift

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.
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) -> 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.
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.
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.
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..
Swift 5
This generic extension will convert an array of objects to a JSON string from which it can either be:
saved to the App's Documents Directory (iOS/MacOS)
output directly to a file on the Desktop (MacOS)
.
extension JSONEncoder {
static func encode<T: Encodable>(from data: T) {
do {
let jsonEncoder = JSONEncoder()
jsonEncoder.outputFormatting = .prettyPrinted
let json = try jsonEncoder.encode(data)
let jsonString = String(data: json, encoding: .utf8)
// iOS/Mac: Save to the App's documents directory
saveToDocumentDirectory(jsonString)
// Mac: Output to file on the user's Desktop
saveToDesktop(jsonString)
} catch {
print(error.localizedDescription)
}
}
static private func saveToDocumentDirectory(_ jsonString: String?) {
guard let path = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let fileURL = path.appendingPathComponent("Output.json")
do {
try jsonString?.write(to: fileURL, atomically: true, encoding: .utf8)
} catch {
print(error.localizedDescription)
}
}
static private func saveToDesktop(_ jsonString: String?) {
let homeURL = FileManager.default.homeDirectoryForCurrentUser
let desktopURL = homeURL.appendingPathComponent("Desktop")
let fileURL = desktopURL.appendingPathComponent("Output.json")
do {
try jsonString?.write(to: fileURL, atomically: true, encoding: .utf8)
} catch {
print(error.localizedDescription)
}
}
}
Example:
struct Person: Codable {
var name: String
var pets: [Pet]
}
struct Pet: Codable {
var type: String
}
extension Person {
static func sampleData() -> [Person] {
[
Person(name: "Adam", pets: []),
Person(name: "Jane", pets: [
Pet(type: "Cat")
]),
Person(name: "Robert", pets: [
Pet(type: "Cat"),
Pet(type: "Rabbit")
])
]
}
}
Usage:
JSONEncoder.encode(from: Person.sampleData())
Output:
This will create the following correctly formatted Output.json file:
[
{
"name" : "Adam",
"pets" : [
]
},
{
"name" : "Jane",
"pets" : [
{
"type" : "Cat"
}
]
},
{
"name" : "Robert",
"pets" : [
{
"type" : "Cat"
},
{
"type" : "Rabbit"
}
]
}
]
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.
extension Array where Element: Encodable {
func asArrayDictionary() throws -> [[String: Any]] {
var data: [[String: Any]] = []
for element in self {
data.append(try element.asDictionary())
}
return data
}
}
extension Encodable {
func asDictionary() throws -> [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)
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.
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
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).
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)&user_id=\(userId)&markupSrcReport=\(markup)"
} catch {
print(error.localizedDescription)
}
request.httpBody = postString.data(using: .utf8)
100% working TESTED
You can try this.
func convertToJSONString(value: AnyObject) -> 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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