I am trying to read the data for "Name" in a JSON file I am hosting using Swift and I seem to only be able to read the whole JSON file and not able to pick out specific data. My JSON file contains this:
[{"Email":"Admin#admin.com","Password":"password","Name":"Admin"}]
The swift code I am using is this:
override func viewDidLoad() {
super.viewDidLoad()
//to get data from external DB
let url = URL(string: "http://localhost/Projects/Test_mobileAPI/test_userInfo.php?email=Admin#admin.com")
let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in
if error != nil{
print("Error Occured")
}
else{
print("Okie")
if let content = data {
do{
//Array
let myJson = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as AnyObject
print("this part works")
print(myJson)
if let diction = myJson as? NSDictionary
{
if let name = myJson["Name"]{
print(name as Any)
}
}
}
catch{
print(error)
}
}
}
}
task.resume()
}
The output I keep getting is this:
Okie
this part works
(
{
Email = "Admin#admin.com";
Name = Admin;
Password = password;
}
)
But I do not get just the value for "Name". Can anyone help me get the value for "Name" (i.e "Admin")
Can you try
if let myJson = try JSONSerialization.jsonObject(with: content) as? [[String:Any]] {
if let first = myJson.first {
print(first["Name"])
}
}
The problem is that the JSON that you're receiving back isn't a Dictionary, it's a single element array with a dictionary in it. So when you do
if let diction = myJson as? NSDictionary
the myJson object is failing the cast to NSDictionary. If you unwrap the array first, you should then be able to reference the dictionary and pick off any keyed values you want:
if let array = myJson as? NSArray
{
if let myDict = array[0] as? NSDictionary
{
if let name = myDict ["Name"]{
print(name as Any)
}
}
}
I'm encoding and decoding to and from JSON strings using JSONSerialization in the class below. I can encode both NSDictionaries & NSArrays and I can decode strings that have been encoded using NSDictionaries but not strings that were encoded from arrays, it barfs at JSONSerialization.jsonObject( ...
I can work without arrays, at a pinch but it would be nice to know why this is happening. Thoughts appreciated
let a = [1,2,3,4,5]
let s = JSON.Encode( a )!
JSON.Decode( s ) // fails
let a = ["a" : 1, "b" : 2, "c" : 3 ]
let s = JSON.Encode( a )!
JSON.Decode( s ) // works
-
class JSON: NSObject {
static func Encode( _ obj: Any ) -> String? {
do {
let data = try JSONSerialization.data(withJSONObject: obj, options:JSONSerialization.WritingOptions(rawValue: 0) )
if let string = NSString(data: data, encoding: String.Encoding.utf8.rawValue) {
return string as String
}
return nil
} catch let error as NSError {
return nil
}
}
static func Decode( _ s: String ) -> (NSDictionary?) {
let data = s.data(using: String.Encoding.utf8, allowLossyConversion: false)!
do {
// fails here to work on anything other than "{ a : b, c : d }"
// hates any [1,2,3] arrays in the string
let json = try JSONSerialization.jsonObject(with: data, options:JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary
return json
} catch let error as NSError {
return nil
}
}
}
You are casting the result to dictionary so it cannot work with something else.
A solution is to make the function generic and specify the expected return type.
I cleaned up the code a bit, basically it’s recommended to make a function throw if it contains a throwing API.
class JSON {
enum JSONError : Error { case typeMismatch }
static func encode( _ obj: Any ) throws -> String {
let data = try JSONSerialization.data(withJSONObject: obj)
return String(data: data, encoding: .utf8)!
}
static func decode<T>( _ s: String ) throws -> T {
let data = Data(s.utf8)
guard let result = try JSONSerialization.jsonObject(with: data) as? T else {
throw JSONError.typeMismatch
}
return result
}
}
let a = [1,2,3,4,5]
do {
let s = try JSON.encode(a)
let u : [Int] = try JSON.decode(s)
print(u)
} catch { print(error) }
Note (as always):
In Swift do not use NSDictionary, NSString and NSErrorand .mutableContainers is completely pointless.
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
}
I've looked around but I don't find an answer to fix this error that has been bugging me. I tried adding a "as! NSMutableArray" but that gave me another error. Any ideas on how to fix it? I converted my project from Objective-C to Swift, so hopefully the code is all good I had 20+ errors now I'm down to 3 errors. Thank you.
Error Message:
'jsonObject' produces 'Any', not the expected contextual result type 'NSMutableArray'
Code for retrieving data from server
// Retrieving Data from Server
func retrieveData() {
let getDataURL = "http://ip/example.org/json.php"
let url: NSURL = NSURL(string: getDataURL)!
do {
let data: NSData = try NSData(contentsOf: url as URL)
jsonArray = JSONSerialization.jsonObject(with: data, options: nil)
}
catch {
print("Error: (data: contentsOf: url)")
}
// Setting up dataArray
var dataArray: NSMutableArray = []
// Looping through jsonArray
for i in 0..<jsonArray.count {
// Create Data Object
let dID: String = (jsonArray[i] as AnyObject).object(forKey: "id") as! String
let dName: String = (jsonArray[i] as AnyObject).object(forKey: "dataName") as! String
let dStatus1: String = (jsonArray[i] as AnyObject).object(forKey: "dataStatus1") as! String
let dStatus2: String = (jsonArray[i] as AnyObject).object(forKey: "dataStatus2") as! String
let dURL: String = (jsonArray[i] as AnyObject).object(forKey: "dataURL") as! String
// Add Data Objects to Data Array
dataArray.add(Data(dataName: dName, andDataStatus1: dStatus1, andDataStatus2: dStatus2, andDataURL: dURL, andDataID: dID))
}
self.myTableView.reloadData()
}
The jsonObject function will return a value of type Any but the jsonArray's type of NSMutableArray. And this function will throw an error if something is wrong, put a try keyword before it. In my experience, let change the type of jsonArray to array of dictionary, so you will extract data with ease.
do {
let data: Data = try Data(contentsOf: url as URL)
let jsonArray: [[String: AnyObject]] = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as! [[String: AnyObject]]
print("json: \(jsonArray)")
for dict in jsonArray {
let dataName = dict["dataName"] as! String
print("dataName: \(dataName)")
}
}
catch {
print("Error: (data: contentsOf: url)")
}
I'm trying to extract information from a JSON file. Is it possible there is something wrong with the JSON output? There seems to be some strange encoding. It's from a blog.
JSON:
[{
"title": "A visit to McSorley\u0027s Old Ale House",
"subtitle": "",
"summary": "\u0026lt;p\u0026gt;McSorley\u0026#39;s Ale House is Manhattan\u0026#39;s oldest pub\u0026lt;/p\u0026gt;"
}]
I successfully create NSData Object, but NSJSONSerialization fails, see the code:
func parseJSON(jsonString: String) -> [String: AnyObject]? {
guard let data: NSData = jsonString.dataUsingEncoding(NSUTF8StringEncoding)
else { return nil }
do {
let dictionary = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String: AnyObject]
return dictionary
} catch {
print("JSON Error: \(error)")
return nil
}
}
Thanks!
Your code works fine the problem is your JSON file, try with another JSON file for example, the following one:
var json = "{\"xyz \":[{\"title\": \"\",\"subtitle\": \"\",\"summary\": \"\"}]}"
func parseJSON(jsonString: String) -> [String: AnyObject]? {
guard let data: NSData = jsonString.dataUsingEncoding(NSUTF8StringEncoding)
else { return nil }
do {
let dictionary = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String: AnyObject]
return dictionary
} catch {
print("JSON Error: \(error)")
return nil
}
}
The output is:
Optional(["xyz": (
{
subtitle = "";
summary = "";
title = "";
}
)])
You're missing the key for the JSON dictionary, if for that I put it some key in the beginning of the JSON to make it works. Nevertheless I strongly recommend you use SwiftyJSON to parse JSON files in an excellent way.
Removing the HTML String
extension String {
/**
Strip the HTML tags for the string passed.
- parameter code: String to strip HTML.
- returns: The new string without HTML tags.
*/
func stripHtmlTags() -> String {
return self.stringByReplacingOccurrencesOfString("<[^>]+>", withString: "", options: .RegularExpressionSearch, range: nil)
}
}
I hope this help you.