I have reduced my dictionary keys successfully in this question as pseudo-code without a real json model. The goal which I accomplished in the previous question is to return only the keys that have matching values. So the output is a dictionary that looks something like this ["WoW": ["#jade", "#kalel"]. Exactly what I needed. Of course there could be other matches and I'd like to return those as well.
Now that I have a proper json model, the reduce function is printing out an empty dictionary [:]. Is it the type in .reduce(into: [String:[String]]() that is causing the issue?
All the data is printing so the json and model structure must be correct.
json
[
{
"id": "tokenID-tqkif48",
"name": "#jade",
"game": "WoW",
"age": "18"
},
{
"id": "tokenID-fvkif21",
"name": "#kalel",
"game": "WoW",
"age": "20"
}
]
UserModel
public typealias Users = [UserModel]
public struct UserModel: Codable {
public let name: String
public let game: String
// etc...
enum CodingKeys: String, CodingKey {
case name
case game
// etc...
Playground
guard let url = Bundle.main.url(forResource: "Users", withExtension: "json") else {
fatalError()
}
guard let data = try? Data(contentsOf: url) else {
fatalError()
}
let decoder = JSONDecoder()
do {
let response = try decoder.decode([UserModel].self, from: data)
for userModel in response {
let userDict: [String:String] = [ userModel.name:userModel.game ]
let reduction = Dictionary(grouping: userDict.keys) { userDict[$0] ?? "" }.reduce(into: [String:[String]](), { (result, element) in
if element.value.count > 1 {
result[element.key] = element.value
}
})
// error catch etc
}
Your code is too complicated. You can group the array by game simply with
let response = try decoder.decode([UserModel].self, from: data)
let reduction = Dictionary(grouping: response, by: {$0.game}).mapValues{ usermodel in usermodel.map{ $0.name}}
UPDATE I may be mistaking what you want to get. There's another code below and please check the results and choose one you want.
If you want to use reduce(into:updateAccumulatingResult:), you can write something like this.
do {
let response = try decoder.decode([UserModel].self, from: data)
let userArray: [(name: String, game: String)] = response.map {($0.name, $0.game)}
let reduction = userArray.reduce(into: [String:[String]]()) {result, element in
if !element.game.isEmpty {
result[element.name, default: []].append(element.game)
}
}
print(reduction)
} catch {
print(error)
}
If you prefer an initializer of Dictionary, this may work:
do {
let response = try decoder.decode([UserModel].self, from: data)
let userArray: [(name: String, games: [String])] = response.map {
($0.name, $0.game.isEmpty ? [] : [$0.game])
}
let reduction = Dictionary(userArray) {old, new in old + new}
print(reduction)
} catch {
print(error)
}
Both output:
["#jade": ["WoW"], "#kalel": ["WoW"]]
Anyway, your way of combining loop, Dictionary(grouping:) and reduce(into:) in addition of userDict.keys is making things too complex than they should be.
ADDITION When you want to get a Dictionary with keys as games:
do {
let response = try decoder.decode([UserModel].self, from: data)
let userArray: [(game: String, name: String)] = response.compactMap {
$0.game.isEmpty ? nil : ($0.game, $0.name)
}
let reduction = userArray.reduce(into: [String:[String]]()) {result, element in
result[element.game, default: []].append(element.name)
}
print(reduction)
} catch {
print(error)
}
Or:
do {
let response = try decoder.decode([UserModel].self, from: data)
let userArray: [(game: String, names: [String])] = response.compactMap {
$0.game.isEmpty ? nil : ($0.game, [$0.name])
}
let reduction = Dictionary(userArray) {old, new in old + new}
print(reduction)
} catch {
print(error)
}
Output:
["WoW": ["#jade", "#kalel"]]
I have a JSON with keys
{
"yearOfManufacture":"20/9/2018",
"carSize":8,
"isNew":true,
"carAssets":[
{
"color":"5761807993001",
"nativeId":"{\"app\":\"1234/Car/Native_App\",\"web\":\" /8888/Car/Native_Car_Desktop\"}"
}
]
}
I am trying to parse using Codable protocol with struct models
struct Cars: Codable {
var yearOfManufacture: String?
var carSize: Int = 0
var isNew: Bool = true
var carAssets: [CarAssests]?
}
struct CarAssests: Codable {
var color: String?
var nativeId: String?
}
I am getting error like The data couldn’t be read because it isn’t in the correct format. I tried using CodingKeys with decoder container not getting the exact type of "nativeId": "{\"app\":\"1234/Car/Native_App\",\"web\":\" /8888/Car/Native_Car_Desktop\"}" not getting exact data type of this.
let decoder = JSONDecoder()
decoder.dataDecodingStrategy = .deferredToData
if let jsonData = jsonString.data(using: .utf8) {
do {
print(jsonData)
let assets = try decoder.decode(Cars.self, from: jsonData)
print(assets)
} catch {
print(error.localizedDescription)
}
}
I bet you are doing something like this:
let jsonString = """
{
"yearOfManufacture": "20/9/2018",
"carSize": 8,
"isNew": true,
"carAssets": [
{
"color": "5761807993001",
"nativeId": "{\"app\":\"1234/Car/Native_App\",\"web\":\" /8888/Car/Native_Car_Desktop\"}"
}
]
}
"""
In a multiline string, both \" and " mean the character ". So you have to write \\" to get the two characters \ and ":
let jsonString = """
{
"yearOfManufacture": "20/9/2018",
"carSize": 8,
"isNew": true,
"carAssets": [
{
"color": "5761807993001",
"nativeId": "{\\"app\\":\\"1234/Car/Native_App\\",\\"web\\":\\" /8888/Car/Native_Car_Desktop\\"}"
}
]
}
"""
I have a complex JSON data.
How can I parse this data?
I've tried, but it does not work.
I need a Dictionary with object (id, time...). But how to get through "1,.."?
And how can I take time begin and end?
"data": {
"1":[
{"id":6524612,
...
"time":{
"begin":"18:50",
"end":"19:20"
},
...
},
"2":[
{
"id":6524613,
...
"time":{
"begin":"18:50",
"end":"19:20"
},
...
},
Where is my mistake?
let broadcastTask = broadcastSession.dataTaskWithRequest(broadcastRequest) { (data, response, error) -> Void in
if error != nil {
print(error.debugDescription)
} else {
do {
let broadcastDict = try NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments) as? Dictionary<String, AnyObject>
if let results = broadcastDict!["data"] as? [Dictionary<String, AnyObject>] {
for obj in results {
let broadcast = Broadcast(broadcastDict: obj)
self.broadcastList.append(broadcast)
}
//Main UI thread
dispatch_async(dispatch_get_main_queue()) {
self.collectionView.reloadData()
}
}
} catch {
}
}
}
broadcastTask.resume()
init(broadcastDict: Dictionary<String, AnyObject>) {
if let category = broadcastDict["id"] as? Int {
self.id = id
}
...
}
If I understand the question correctly:
The first problem seems to be that you are trying to cast the "data" dictionary to an array of dictionaries. This will always fail because your data object is a dictionary and not an array.
Once you correct that problem you will run into trouble with your loop. Try this:
for (key, value) in results {
let broadcast = Broadcast(broadcastDict: value)
self.broadcastList.append(broadcast)
}
Now you are sending the dictionary that your Broadcast object is expecting.
so am trying to learn about JSON parsing, i want to extract some information from these fields..
index = 90;
property1 = {
href = "http://www.bodybuilding.com/exercises/detail/view/name/supine-one-arm-overhead-throw";
text = "Supine One-Arm Overhead Throw";
};
property2 = {
href = "http://www.bodybuilding.com/exercises/finder/lookup/filter/muscle/id/13/muscle/abdominals";
text = Abdominals;
};
property3 = (
{
href = "http://www.bodybuilding.com/exercises/detail/view/name/supine-one-arm-overhead-throw";
src = "http://www.bodybuilding.com/exercises/exerciseImages/sequences/839/Male/m/839_1.jpg";
text = "";
},
i can get a chunk of data, the problem is when i try to sort this information out... here is my code
func parseDictionary(dictionary: [String: AnyObject]) {
if let array: AnyObject = dictionary["results"] {
for resultDict in array as![AnyObject] {
if let resultDict = resultDict as? [String:AnyObject] {
if let wrapperType = resultDict["wrapperType"] as? String {
if let kind = resultDict["kind"] as? String {
print("wrapperType: \(wrapperType), kind: \(kind)")
}
}
} else {
print("expected a dictionary")
}
}
} else {
print("expected results array")
}
}
the error am getting is..
//Could not cast value of type '__NSCFDictionary' (0x1014c8a60) to //'NSArray' (0x1014c8470).
Your line:
for resultDict in array as![AnyObject] {
Needs to change to
for resultDict in array as![String: AnyObject] {
[AnyObject] is shorthand for Array<AnyObject>, whereas [String: AnyObject] is shorthand for Dictionary<String, AnyObject>, which explains your error.
Is there a way to properly deserialize a JSON response to Swift objects resp. using DTOs as containers for fixed JSON APIs?
Something similar to http://james.newtonking.com/json or something like this example from Java
User user = jsonResponse.readEntity(User.class);
whereby jsonResponse.toString() is something like
{
"name": "myUser",
"email": "user#example.com",
"password": "passwordHash"
}
SWIFT 4 Update
Since you give a very simple JSON object the code prepared for to handle that model. If you need more complicated JSON models you need to improve this sample.
Your Custom Object
class Person : NSObject {
var name : String = ""
var email : String = ""
var password : String = ""
init(JSONString: String) {
super.init()
var error : NSError?
let JSONData = JSONString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
let JSONDictionary: Dictionary = NSJSONSerialization.JSONObjectWithData(JSONData, options: nil, error: &error) as NSDictionary
// Loop
for (key, value) in JSONDictionary {
let keyName = key as String
let keyValue: String = value as String
// If property exists
if (self.respondsToSelector(NSSelectorFromString(keyName))) {
self.setValue(keyValue, forKey: keyName)
}
}
// Or you can do it with using
// self.setValuesForKeysWithDictionary(JSONDictionary)
// instead of loop method above
}
}
And this is how you invoke your custom class with JSON string.
override func viewDidLoad() {
super.viewDidLoad()
let jsonString = "{ \"name\":\"myUser\", \"email\":\"user#example.com\", \"password\":\"passwordHash\" }"
var aPerson : Person = Person(JSONString: jsonString)
println(aPerson.name) // Output is "myUser"
}
I recommend that you use code generation (http://www.json4swift.com) to create native models out of the json response, this will save your time of parsing by hand and reduce the risk of errors due to mistaken keys, all elements will be accessible by model properties, this will be purely native and the models will make more sense rather checking the keys.
Your conversion will be as simple as:
let userObject = UserClass(userDictionary)
print(userObject!.name)
Swift 2: I really like the previous post of Mohacs! To make it more object oriented, i wrote a matching Extension:
extension NSObject{
convenience init(jsonStr:String) {
self.init()
if let jsonData = jsonStr.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
{
do {
let json = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as! [String: AnyObject]
// Loop
for (key, value) in json {
let keyName = key as String
let keyValue: String = value as! String
// If property exists
if (self.respondsToSelector(NSSelectorFromString(keyName))) {
self.setValue(keyValue, forKey: keyName)
}
}
} catch let error as NSError {
print("Failed to load: \(error.localizedDescription)")
}
}
else
{
print("json is of wrong format!")
}
}
}
custom classes:
class Person : NSObject {
var name : String?
var email : String?
var password : String?
}
class Address : NSObject {
var city : String?
var zip : String?
}
invoking custom classes with JSON string:
var jsonString = "{ \"name\":\"myUser\", \"email\":\"user#example.com\", \"password\":\"passwordHash\" }"
let aPerson = Person(jsonStr: jsonString)
print(aPerson.name!) // Output is "myUser"
jsonString = "{ \"city\":\"Berlin\", \"zip\":\"12345\" }"
let aAddress = Address(jsonStr: jsonString)
print(aAddress.city!) // Output is "Berlin"
Yet another JSON handler I wrote:
https://github.com/dankogai/swift-json
With it you can go like this:
let obj:[String:AnyObject] = [
"array": [JSON.null, false, 0, "", [], [:]],
"object":[
"null": JSON.null,
"bool": true,
"int": 42,
"double": 3.141592653589793,
"string": "a α\t弾\n𪚲",
"array": [],
"object": [:]
],
"url":"http://blog.livedoor.com/dankogai/"
]
let json = JSON(obj)
json.toString()
json["object"]["null"].asNull // NSNull()
json["object"]["bool"].asBool // true
json["object"]["int"].asInt // 42
json["object"]["double"].asDouble // 3.141592653589793
json["object"]["string"].asString // "a α\t弾\n𪚲"
json["array"][0].asNull // NSNull()
json["array"][1].asBool // false
json["array"][2].asInt // 0
json["array"][3].asString // ""
As you see no !? needed between subscripts.
In addition to that you can apply your own schema like this:
//// schema by subclassing
class MyJSON : JSON {
override init(_ obj:AnyObject){ super.init(obj) }
override 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 }
var url: String? { return self["url"].asString }
var array :MyJSON { return MyJSON(self["array"]) }
var object:MyJSON { return MyJSON(self["object"]) }
}
let myjson = MyJSON(obj)
myjson.object.null // NSNull?
myjson.object.bool // Bool?
myjson.object.int // Int?
myjson.object.double // Double?
myjson.object.string // String?
myjson.url // String?
There's a great example by Apple for deserializing JSON with Swift 2.0
The trick is to use the guard keyword and chain the assignments like so:
init?(attributes: [String : AnyObject]) {
guard let name = attributes["name"] as? String,
let coordinates = attributes["coordinates"] as? [String: Double],
let latitude = coordinates["lat"],
let longitude = coordinates["lng"],
else {
return nil
}
self.name = name
self.coordinates = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
}
I personally prefer native parsing vs any 3rd party, as it is transparent and magic-less. (and bug less?)
Using quicktype, I generated your model and serialization helpers from your sample:
import Foundation
struct User: Codable {
let name: String
let email: String
let password: String
}
extension User {
static func from(json: String, using encoding: String.Encoding = .utf8) -> OtherUser? {
guard let data = json.data(using: encoding) else { return nil }
return OtherUser.from(data: data)
}
static func from(data: Data) -> OtherUser? {
let decoder = JSONDecoder()
return try? decoder.decode(OtherUser.self, from: data)
}
var jsonData: Data? {
let encoder = JSONEncoder()
return try? encoder.encode(self)
}
var jsonString: String? {
guard let data = self.jsonData else { return nil }
return String(data: data, encoding: .utf8)
}
}
Then parse User values like this:
let user = User.from(json: """{
"name": "myUser",
"email": "user#example.com",
"password": "passwordHash"
}""")!
I wrote this small open-source library recently that lets you quickly and easily deserialize dictionaries into Swift objects: https://github.com/isair/JSONHelper
Using it, deserializing data becomes as easy as this:
var myInstance = MyClass(data: jsonDictionary)
or
myInstance <-- jsonDictionary
And models need to look only like this:
struct SomeObjectType: Deserializable {
var someProperty: Int?
var someOtherProperty: AnotherObjectType?
var yetAnotherProperty: [YetAnotherObjectType]?
init(data: [String: AnyObject]) {
someProperty <-- data["some_key"]
someOtherProperty <-- data["some_other_key"]
yetAnotherProperty <-- data["yet_another_key"]
}
}
Which, in your case, would be:
struct Person: Deserializable {
var name: String?
var email: String?
var password: String?
init(data: [String: AnyObject]) {
name <-- data["name"]
email <-- data["email"]
password <-- data["password"]
}
}
If you would like parse from and to json without the need to manually map keys and fields, then you could also use EVReflection. You can then use code like:
var user:User = User(json:jsonString)
or
var jsonString:String = user.toJsonString()
The only thing you need to do is to use EVObject as your data objects base class.
See the GitHub page for more detailed sample code
I am expanding upon Mohacs and Peter Kreinz's excellent answers just a bit to cover the array of like objects case where each object contains a mixture of valid JSON data types. If the JSON data one is parsing is an array of like objects containing a mixture of JSON data types, the do loop for parsing the JSON data becomes this.
// Array of parsed objects
var parsedObjects = [ParsedObject]()
do {
let json = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as [Dictionary<String, AnyObject>]
// Loop through objects
for dict in json {
// ParsedObject is a single instance of an object inside the JSON data
// Its properties are a mixture of String, Int, Double and Bool
let parsedObject = ParsedObject()
// Loop through key/values in object parsed from JSON
for (key, value) in json {
// If property exists, set the value
if (parsedObject.respondsToSelector(NSSelectorFromString(keyName))) {
// setValue can handle AnyObject when assigning property value
parsedObject.setValue(keyValue, forKey: keyName)
}
}
parsedObjects.append(parsedObject)
}
} catch let error as NSError {
print("Failed to load: \(error.localizedDescription)")
}
This way lets you get the user from a URL. It's parse the NSData to a NSDictionary and then to your NSObject.
let urlS = "http://api.localhost:3000/"
func getUser(username: Strung) -> User {
var user = User()
let url = NSURL(string: "\(urlS)\(username)")
if let data = NSData(contentsOfURL: url!) {
setKeysAndValues(user, dictionary: parseData(data))
}
return user
}
func setKeysAndValues (object : AnyObject, dictionary : NSDictionary) -> AnyObject {
for (key, value) in dictionary {
if let key = key as? String, let value = value as? String {
if (object.respondsToSelector(NSSelectorFromString(key))) {
object.setValue(value, forKey: key)
}
}
}
return object
}
func parseData (data : NSData) -> NSDictionary {
var error: NSError?
return NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &error) as! NSDictionary
}
In Swift 4, You can use the Decoding, CodingKey protocols to deserialize the JSON response:
Create the class which confirm the decodable protocol
class UserInfo: Decodable
Create members of the class
var name: String
var email: String
var password: String
Create JSON key enum which inherits from CodingKey
enum UserInfoCodingKey: String, CodingKey {
case name
case password
case emailId
}
Implement init
required init(from decoder: Decoder) throws
The whole class look like :
Call Decoder
// jsonData is JSON response and we get the userInfo object
let userInfo = try JsonDecoder().decode(UserInfo.self, from: jsonData)
You do this by using NSJSONSerialization. Where data is your JSON.
First wrap it in an if statement to provide some error handling capablity
if let data = data,
json = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String: AnyObject] {
// Do stuff
} else {
// Do stuff
print("No Data :/")
}
then assign them:
let email = json["email"] as? String
let name = json["name"] as? String
let password = json["password"] as? String
Now, This will show you the result:
print("Found User iname: \(name) with email: \(email) and pass \(password)")
Taken from this Swift Parse JSON tutorial. You should check out the tutorial as it goes a lot more in depth and covers better error handling.