JSON Parsing in Swift 3 - json

Question

Has anyone been able to find a way to parse through JSON files in Swift 3? I have been able to get the data to return but I am unsuccessful when it comes to breaking the data down into specific fields. I would post sample code but I've gone through so many different methods unsuccessfully and haven't saved any. The basic format I want to parse through is something like this. Thanks in advance.
{
"Language": {
"Field":[
{
"Number":"976",
"Name":"Test"
},
{
"Number":"977",
"Name":"Test"
}
]
}
}

Answer 1

Have you tried JSONSerialization.jsonObject(with:options:)?
var jsonString = "{" +
"\"Language\": {" +
"\"Field\":[" +
"{" +
"\"Number\":\"976\"," +
"\"Name\":\"Test\"" +
"}," +
"{" +
"\"Number\":\"977\"," +
"\"Name\":\"Test\"" +
"}" +
"]" +
"}" +
"}"
var data = jsonString.data(using: .utf8)!
let json = try? JSONSerialization.jsonObject(with: data)
Swift sometimes produces some very odd syntax.
if let number = json?["Language"]??["Field"]??[0]?["Number"] as? String {
print(number)
}
Everything in the JSON object hierarchy ends up getting wrapped as an optional (ie. AnyObject?). Array<T> subscript returns a non-optional T. For this JSON, which is wrapped in an optional, array subscript returns Optional<AnyObject>. However, Dictionary<K, V> subscript returns an Optional<V>. For this JSON, subscript returns the very odd looking
Optional<Optional<AnyObject>> (ie. AnyObject??).
json is an Optional<AnyObject>.
json?["Language"] returns an Optional<Optional<AnyObject>>.
json?["Language"]??["Field"] returns an Optional<Optional<AnyObject>>.
json?["Language"]??["Field"]??[0] returns an Optional<AnyObject>.
json?["Language"]??["Field"]??[0]?["Number"] returns an Optional<Optional<AnyObject>>.
json?["Language"]??["Field"]??[0]?["Number"] as? String returns an Optional<String>.
The Optional<String> is then used by the if let syntax to product a String.
Final note: iterating the field array looks like this.
for field in json?["Language"]??["Field"] as? [AnyObject] ?? [] {
if let number = field["Number"] as? String {
print(number)
}
}
Swift 4 Update
Swift 4 makes this all much easier to deal with. Again we will start with your test data (""" makes this so much nicer).
let data = """
{
"Language": {
"Field":[
{
"Number":"976",
"Name":"Test"
},
{
"Number":"977",
"Name":"Test"
}
]
}
}
""".data(using: .utf8)!
Next we can define classes around the objects used in your JSON.
struct Object: Decodable {
let language: Language
enum CodingKeys: String, CodingKey { case language="Language" }
}
struct Language: Decodable {
let fields: [Field]
enum CodingKeys: String, CodingKey { case fields="Field" }
}
struct Field: Decodable {
let number: String
let name: String
enum CodingKeys: String, CodingKey { case number="Number"; case name="Name" }
}
The CodingKeys enum is how struct properties are mapped to JSON object member strings. This mapping is done automagically by Decodable.
Parsing the JSON now is simple.
let object = try! JSONDecoder().decode(Object.self, from: data)
print(object.language.fields[0].name)
for field in object.language.fields {
print(field.number)
}

Answer 2

In Xcode 8 and Swift 3 id now imports as Any rather than AnyObject
This means that JSONSerialization.jsonObject(with: data) returns Any. So you have to cast the json data to a specific type like [String:Any]. Same applies to the next fields down the json.
var jsonString = "{" +
"\"Language\": {" +
"\"Field\":[" +
"{" +
"\"Number\":\"976\"," +
"\"Name\":\"Test1\"" +
"}," +
"{" +
"\"Number\":\"977\"," +
"\"Name\":\"Test2\"" +
"}" +
"]" +
"}" +
"}"
var data = jsonString.data(using: .utf8)!
if let parsedData = try? JSONSerialization.jsonObject(with: data) as! [String:Any] {
let language = parsedData["Language"] as! [String:Any]
print(language)
let field = language["Field"] as! [[String:Any]]
let name = field[0]["Name"]!
print(name) // ==> Test1
}
In practice you would probably want some specific field buried in the json. Lets assume it's the Name field of the first element of Field array. You can use a chain of unwraps like this to safely access the field:
var data = jsonString.data(using: .utf8)!
if let json = try? JSONSerialization.jsonObject(with: data) as? [String:Any],
let language = json?["Language"] as? [String:Any],
let field = language["Field"] as? [[String:Any]],
let name = field[0]["Name"] as? String, field.count > 0 {
print(name) // ==> Test1
} else {
print("bad json - do some recovery")
}
Also you may want to check Apple's Swift Blog Working with JSON in Swift

Answer 3

Shoving JSON into a string manually is a pita. Why don't you just put the JSON into a file and read that in?
Swift 3:
let bundle = Bundle(for: type(of: self))
if let theURL = bundle.url(forResource: "response", withExtension: "json") {
do {
let data = try Data(contentsOf: theURL)
if let parsedData = try? JSONSerialization.jsonObject(with: data) as! [String:Any] {
grok(parsedData)
}
} catch {
print(error)
}
}

Answer 4

override func viewDidLoad() {
super.viewDidLoad()
let url=URL(string:"http://api.androidhive.info/contacts/")
do {
let allContactsData = try Data(contentsOf: url!)
let allContacts = try JSONSerialization.jsonObject(with: allContactsData, options: JSONSerialization.ReadingOptions.allowFragments) as! [String : AnyObject]
if let arrJSON = allContacts["contacts"] {
for index in 0...arrJSON.count-1 {
let aObject = arrJSON[index] as! [String : AnyObject]
names.append(aObject["name"] as! String)
contacts.append(aObject["email"] as! String)
}
}
print(names)
print(contacts)
self.tableView.reloadData()
}
catch {
}
}

Answer 5

JSON Parsing in swift 4 using Decodable Protocol :
I create a mocky file using your json object :
http://www.mocky.io/v2/5a280c282f0000f92c0635e6
Here is the code to parse the JSON :
Model Creation :
import UIKit
struct Item : Decodable {
// Properties must be the same name as specified in JSON , else it will return nil
var Number : String
var Name : String
}
struct Language : Decodable {
var Field : [Item]
}
struct Result : Decodable {
var Language : Language
}
You can use optional in the model if you are uncertain that something might be missing in JSON file.
This is the parsing Logic :
class ViewController: UIViewController {
let url = "http://www.mocky.io/v2/5a280c282f0000f92c0635e6"
private func parseJSON() {
guard let url = URL(string: url) else { return }
let session = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data else { return }
guard let result = try? JSONDecoder().decode(Result.self, from: data) else { return }
print("\n\nResult : \(result)")
}
session.resume()
}
override func viewDidLoad() {
super.viewDidLoad()
parseJSON()
}
}
The Print Output :
Result : Result(Language: JSON_Parsing.Language(Field: [JSON_Parsing.Item(Number: "976", Name: "Test"), JSON_Parsing.Item(Number: "977", Name: "Test")]))
This the github Project link. You can check.

Answer 6

JSON Parsing using Swift 4 in Simple WAY
let url = URL(string: "http://mobileappdevelop.co/TIPIT/webservice/get_my_groups?user_id=5")
URLSession.shared.dataTask(with:url!, completionHandler: {(data, response, error) in
guard let data = data, error == nil else { return }
do {
let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as! [String:Any]
print(json)
let posts = json["Field"] as? [[String: Any]] ?? []
print(posts)
} catch let error as NSError {
print(error)
}
}).resume()
}

Answer 7

Use SwiftJson library. I think its very easy way to parse.
let count: Int? = json["Field"].array?.count
if let ct = count {
for index in 0...ct-1{
let number = json ["Field"][index]["number"].string
let name = json ["Field"][index]["name"].string
....
like this .

Answer 8

dict = {
message = "Login successfully.";
status = 1;
"user_details" = (
{
dob = "1900-11-18";
email = "rizwan#gmail.com";
gender = male;
name = Rizwan;
nickname = Shaikh;
"profile_pic" = "1483434421.jpeg";
"social_id" = "<null>";
"user_id" = 2;
}
);
}
We can parse above json in Swift 3 as
var dict2 = dict as! [String : Any]
print(dict);
let demoStr = dict2["message"] as! String
print(demoStr)
let demoArray = dict2["user_details"] as! [Any]
let demoDict = demoArray[0] as! [String:Any]
print(demoDict["dob"]!)