ObjectMapper how to map different JSON based objects
I am using ObjectMapper ( https://github.com/Hearst-DD/ObjectMapper ) to map my JSON to Swift objects.
Let's say I have this JSON structure:
{
animals: [
{
"type": "Cat",
"weight": 23,
"catchMice": true
},
{
"type": "Fish",
"weight": 1,
"swim": true
}
]
}
I have the following Swift objects:
class Foo: Mappable {
var animals: [Animal] = []
func mapping(map: Map) {
animals <- map["animals"] //But I want to be able to distinguish between Cat and Fish objects here
}
}
class Animal: Mappable {
var type: String?
var weight: Double?
required init?(map: Map) {}
func mapping(map: Map) {
type <- map["type"]
weight <- map["weight"]
}
}
class Cat: Animal { // How do I make use of this class
var catchMice: Bool?
}
class Fish: Animal { // How do I make use of this class
var swim: Bool?
}
How can I distinguish between Cat
and Fish
in my display using the key type
in my JSON objects? Thank!
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4 answers
the details
- Xcode 10.2.1 (10E1001), Swift 5
JSON file
{
"animals": [
{
"id": 1,
"name": "Cat",
"type": "cat",
"weight": 23,
"area": ["home", "street"],
"can_climb_trees": true,
"competence": [
{ "id": 1, "name": "to catch mouse" },
{ "id": 2, "name": "to mew" },
{ "id": 3, "name": "to wake people up in the morning" },
{ "id": 4, "name": "to eat fish" }
]
},
{
"id": 2,
"name": "fish",
"type": "fish",
"weight": 1,
"area": ["ocean", "lake"],
"can_swim": false,
"competence": [
{ "id": 5, "name": "to swim" },
{ "id": 6, "name": "to tease a cat" }
]
},
{
"id": 3,
"name": "dog",
"weight": 55,
"area": ["house", "street"],
"competence": [
{ "id": 5, "name": "to bring newspaper" },
{ "id": 6, "name": "to a good booy" }
]
},
{
"id": 4,
"name": "Cat",
"type": "cat",
"weight": 23,
"area": ["home", "street"],
"can_climb_trees": true,
"competence": [
{ "id": 1, "name": "to catch mouse" },
{ "id": 2, "name": "to mew" },
{ "id": 3, "name": "to wake people up in the morning" },
{ "id": 4, "name": "to eat fish" }
]
}
]
}
ObjectMapper Sample
Detect objects in an array
import Foundation
import ObjectMapper
class AnimalsArrayTransformType: TransformType {
public typealias Object = [Animal]
public typealias JSON = [[String: Any]]
func transformToJSON(_ value: [Animal]?) -> [[String : Any]]? {
guard let animals = value else { return nil }
return animals.map { $0.toJSON() }
}
func transformFromJSON(_ value: Any?) -> [Animal]? {
guard let animals = value as? [[String: Any]] else { return nil }
return animals.compactMap { dictionary -> Animal? in
if let cat = Cat(JSON: dictionary) { return cat }
if let fish = Fish(JSON: dictionary) { return fish }
if let animal = Animal(JSON: dictionary) { return animal }
return nil
}
}
}
Mapping classes
import Foundation
import ObjectMapper
class Animals: Mappable, CustomStringConvertible {
private(set) var animals: [Animal] = []
required init?(map: Map) { }
func mapping(map: Map) {
animals <- (map["animals"], AnimalsArrayTransformType())
}
}
class BaseObject: Mappable, CustomStringConvertible {
private(set) var id: Int?
private(set) var name: String?
required init?(map: Map) { mapping(map: map) }
func mapping(map: Map) {
id <- map["id"]
name <- map["name"]
}
}
class Animal: BaseObject {
private(set) var type: String?
private(set) var weight: Double?
private(set) var area: [String]?
private(set) var competence: [BaseObject]?
required init?(map: Map) { super.init(map: map) }
override func mapping(map: Map) {
super.mapping(map: map)
type <- map["type"]
weight <- map["weight"]
area <- map["area"]
competence <- map["competence"]
}
}
class Cat: Animal {
private(set) var canClimbTrees: Bool?
required init?(map: Map) {
super.init(map: map)
if canClimbTrees == nil { return nil }
}
override func mapping(map: Map) {
super.mapping(map: map)
canClimbTrees <- map["can_climb_trees"]
}
}
class Fish: Animal {
private(set) var canSwim: Bool?
required init?(map: Map) {
super.init(map: map)
if canSwim == nil { return nil }
}
override func mapping(map: Map) {
super.mapping(map: map)
canSwim <- map["can_swim"]
}
}
Helpers
extension Mappable {
var description: String {
return toJSONString(prettyPrint: true) ?? "\(self)"
}
}
Usage (read JSON from file)
func sample() {
if let path = Bundle.main.path(forResource: "data", ofType: "json") {
do {
let text = try String(contentsOfFile: path, encoding: .utf8)
if let dict = try JSONSerialization.jsonObject(with: text.data(using: .utf8)!, options: JSONSerialization.ReadingOptions.allowFragments) as? [String: Any] {
if let data = Animals(JSON: dict) {
print(data.animals.map {"class: \(type(of: $0))" }.joined(separator: ", ") )
// class: Cat, class: Fish, class: Animal
print("===============\n\(data)")
}
}
}catch {
print("\(error.localizedDescription)")
}
}
}
Sample to be encoded
Detect objects in an array
class Animals: Codable {
fileprivate enum CodingKeys: String, CodingKey {
case animals
}
private(set) var animals: [Animal]
required init(from decoder: Decoder) throws {
self.animals = []
let container = try decoder.container(keyedBy: CodingKeys.self)
var unkeyedDecodingContainer = try container.nestedUnkeyedContainer(forKey: .animals)
while !unkeyedDecodingContainer.isAtEnd {
if let obj = try? unkeyedDecodingContainer.decode(Cat.self) {
animals.append(obj)
continue
}
if let obj = try? unkeyedDecodingContainer.decode(Fish.self) {
animals.append(obj)
continue
}
if let obj = try? unkeyedDecodingContainer.decode(Animal.self) {
animals.append(obj)
continue
}
}
}
}
Mapping classes
enum AnimalType: String, Codable {
case cat = "cat", fish = "fish"
}
class BaseObject: Codable {
private(set) var id: Int?
private(set) var name: String?
}
class Animal: BaseObject {
private(set) var type: AnimalType?
private(set) var weight: Int?
private(set) var area: [String]?
private(set) var competence: [BaseObject]?
private enum CodingKeys: String, CodingKey {
case type, weight, area, competence
}
override func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encodeIfPresent(type, forKey: .type)
try container.encodeIfPresent(weight, forKey: .weight)
try container.encodeIfPresent(area, forKey: .area)
try container.encodeIfPresent(competence, forKey: .competence)
try super.encode(to: encoder)
}
required init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
type = try container.decodeIfPresent(AnimalType.self, forKey: .type)
weight = try container.decodeIfPresent(Int.self, forKey: .weight)
area = try container.decodeIfPresent([String].self, forKey: .area)
competence = try container.decodeIfPresent([BaseObject].self, forKey: .competence)
try super.init(from: decoder)
}
}
class Cat: Animal {
private(set) var canClimbTrees: Bool
private enum CodingKeys: String, CodingKey {
case canClimbTrees = "can_climb_trees"
}
override func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encodeIfPresent(canClimbTrees, forKey: .canClimbTrees)
try super.encode(to: encoder)
}
required init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.canClimbTrees = try container.decode(Bool.self, forKey: .canClimbTrees)
try super.init(from: decoder)
}
}
class Fish: Animal {
private(set) var canSwim: Bool
enum CodingKeys: String, CaseIterable, CodingKey {
case canSwim = "can_swim"
}
override func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encodeIfPresent(canSwim, forKey: .canSwim)
try super.encode(to: encoder)
}
required init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.canSwim = try container.decode(Bool.self, forKey: .canSwim)
try super.init(from: decoder)
}
}
Helpers
extension Decodable where Self : Encodable {
dynamic func format(options: JSONEncoder.OutputFormatting) -> String {
let encoder = JSONEncoder()
encoder.outputFormatting = options
do {
let jsonData = try encoder.encode(self)
if let jsonString = String(data: jsonData, encoding: .utf8) { return "\(jsonString)" }
} catch {
print("\(error.localizedDescription)")
}
return "nil"
}
}
Usage (read JSON from file)
func sample() {
if let path = Bundle.main.path(forResource: "data", ofType: "json") {
do {
guard let data = try String(contentsOfFile: path, encoding: .utf8).data(using: .utf8) else { return }
let decoder = JSONDecoder()
let result = try decoder.decode(Animals.self, from: data)
print(result.animals.map {"\(type(of: $0))" } )
//print("===============")
//print(result.format(options: .prettyPrinted))
} catch let error {
print("\(error.localizedDescription)")
}
}
}
Output
["Cat", "Fish", "Animal", "Cat"]
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My solution is using the ObjectMapper library for fast.
If you have this:
{
"animals": [{
"type": "Cat",
"weight": 23,
"catchMice": true
},
{
"type": "Fish",
"weight": 1,
"swim": true
}
]
}
This website returns your complete object
import Foundation
import ObjectMapper
class Main: Mappable {
var animals: [Animals]?
required init?(map: Map){
}
func mapping(map: Map) {
animals <- map["animals"]
}
}
class Animals: Mappable {
var type: String?
var weight: NSNumber?
var catchMice: Bool?
required init?(map: Map){
}
func mapping(map: Map) {
type <- map["type"]
weight <- map["weight"]
catchMice <- map["catchMice"]
}
}
I have work on this project which helps to create your displayables for ObjectMappable (swift) library.
https://github.com/andreycattalin/JSONtoSwiftObjectMapper
Current version: http://izee.ro/andrey/JSONtoSwiftObjectMapper/
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Simple example as follow
//
// ViewController.swift
// TriyalJSON
//
// Created by Mac on 19/02/19.
// Copyright © 2019 shital. All rights reserved.
//
import UIKit
class ViewController: UIViewController,UITableViewDelegate, UITableViewDataSource {
@IBOutlet weak var mytable: UITableView!
var arrmain = [GETArrayData]()
override func viewDidLoad() {
super.viewDidLoad()
getdata()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func getdata()
{
let dict = [
"name":"shital",
"address":"pune"
]
APIManager.sharedInstance.getdata(parms: dict, onsuccess: { (responsedata, anystring) in
print(responsedata,anystring)
self.arrmain = responsedata
let str = self.arrmain[0]
print("Email-",str.email)
self.mytable.reloadData()
}) { (error1, error2) in
print(error1,error2)
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.arrmain.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:UITableViewCell = mytable.dequeueReusableCell(withIdentifier: "TableViewCell") as! UITableViewCell
let str1 = self.arrmain[indexPath.row]
cell.textLabel?.text = str1.email
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 400.0
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let obj = storyboard?.instantiateViewController(withIdentifier: "ViewControllerFrist") as! ViewControllerFrist
// ViewControllerFrist.arrpass = self.arrmain
var strpass = self.arrmain[indexPath.row]
obj.arrpass = [strpass]
// obj.arrpass = self.arrmain
self.navigationController? .pushViewController(obj, animated: true)
}
}
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//
// ViewControllerFrist.swift
// TriyalJSON
//
// Created by Mac on 20/02/19.
// Copyright © 2019 shital. All rights reserved.
//
import UIKit
class ViewControllerFrist: UIViewController,UITableViewDelegate,UITableViewDataSource {
var arrpass = [GETArrayData]()
static let fristobject = ViewControllerFrist()
@IBOutlet weak var mytableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print(self.arrpass.count)
return self.arrpass.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:TableViewCell = mytableView.dequeueReusableCell(withIdentifier: "TableViewCell") as! TableViewCell
let str = self.arrpass[indexPath.row]
cell.textLabel1.text = str.email
cell.textLabel2.text = "\(str.id)"
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 300.0
}
}
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------------------------------
//
// APIManager.swift
// TriyalJSON
//
// Created by Mac on 19/02/19.
// Copyright © 2019 shital. All rights reserved.
//
import UIKit
import Foundation
import Alamofire
import ObjectMapper
class APIManager: NSObject {
static let sharedInstance = APIManager()
func getdata(parms:[String:Any], onsuccess:@escaping([GETArrayData],String?) ->Void,onfailure:@escaping(String?,String?) ->Void)
{
let url = URL.init(string: "https://jsonplaceholder.typicode.com/comments")
let headrs : HTTPHeaders = ["content-type":"application/json"]
Alamofire.request(url!, method: .get, parameters: parms, encoding: JSONEncoding.default, headers: headrs).responseJSON
{
response in
switch response.result{
case .success:
// let string = NSString(data: response.data!, encoding: String.Encoding.utf8.rawValue)
// print("string:\(String(describing: string))")
do{
let jsonResponse = try JSONSerialization.jsonObject(with: response.data!, options: []) as! AnyObject
//let userdetails = Mapper<DataClasss>() .mapArray(JSONObject: jsonResponse)
// let userdetalis = Mapper<GETArrayData>() .mapArray(JSONString: jsonResponse)
let userdetails = Mapper<GETArrayData>() .mapArray(JSONObject: jsonResponse)
print(jsonResponse)
if jsonResponse != nil
{
onsuccess(userdetails!,"success")
}
else
{
onfailure((response.error?.localizedDescription)!,"fail")
}
}catch let parsingError{
print("error",parsingError)
onfailure((response.error?.localizedDescription)!,"fail")
}
break
case.failure(let error):
print(error)
onfailure((response.error?.localizedDescription)!,"fail")
}
}
}
}
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--------------------
//
// SecendViewController.swift
// ITGURUassignment
//
// Created by Mac on 18/02/19.
// Copyright © 2019 shital. All rights reserved.
//
import UIKit
class SecendViewController: UIViewController {
@IBOutlet weak var textName: UITextField!
@IBOutlet weak var txtEmail: UITextField!
@IBOutlet weak var txtFeatureTitle: UITextField!
@IBOutlet weak var txtFeatureDescription: UITextView!
@IBOutlet weak var txtUseCase: UITextView!
@IBOutlet weak var btnlow: UIButton!
var strresult = ""
@IBAction func sendRequestPressed(_ sender: UIButton) {
var strname = self.textName.text!
var stremail = self.txtEmail.text!
var strtitle = self.txtFeatureTitle.text!
if strname.count <= 0
{
print("Enter Frist Name")
}
else if stremail.count <= 0 {
print("enter last name")
}
else if strtitle.count <= 0 {
print("Enter feature title")
}
else if self.strresult.count <= 0
{
print("Button not selected:\(strresult)")
}
else
{
print("Button selected:\(strresult)")
let dict = [
"AppID":"67-5555545ete",
"FeatureTitle":"\(self.txtFeatureTitle.text!)",
"UserName":"laura",
"UserEmail":"\(self.txtEmail.text!)",
"Priority":self.strresult,
"Description":"\(self.txtFeatureDescription.text ?? "")",
"UseCase":"\(self.txtUseCase.text ?? "")",
"DeviceType":"iphone"
]
print(dict)
}
}
@IBAction func btnhighpressed(_ sender: UIButton) {
self.strresult = "H"
print(strresult)
self.btnhigh.setImage(imgselected, for: .normal)
self.btnlow.setImage(imgunselected, for: .normal)
self.btnmedium.setImage(imgunselected, for: .normal)
}
@IBAction func btnlowpressed(_ sender: UIButton) {
self.strresult = "L"
print(strresult)
self.btnhigh.setImage(imgunselected, for: .normal)
self.btnlow.setImage(imgselected, for: .normal)
self.btnmedium.setImage(imgunselected, for: .normal)
}
@IBAction func btnmedium(_ sender: UIButton) {
self.strresult = "M"
print(strresult)
self.btnhigh.setImage(imgunselected, for: .normal)
self.btnlow.setImage(imgunselected, for: .normal)
self.btnmedium.setImage(imgselected, for: .normal)
}
@IBOutlet weak var btnmedium: UIButton!
@IBOutlet weak var btnhigh: UIButton!
let imgselected = UIImage.init(named: "Selected")
let imgunselected = UIImage.init(named: "Unselected")
override func viewDidLoad() {
super.viewDidLoad()
self.btnhigh.setImage(imgunselected, for: .normal)
self.btnlow.setImage(imgunselected, for: .normal)
self.btnmedium.setImage(imgunselected, for: .normal)
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
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//
// ViewController.swift
// ITGURUassignment
//
// Created by Mac on 18/02/19.
// Copyright © 2019 shital. All rights reserved.
//
import UIKit
class ViewController: UIViewController,UITableViewDelegate,UITableViewDataSource {
// var arrCountryList = [CountryDetails]()
var arruserdetalis = [USERdetalis]()
// var usermasterdetails = USERdetalis()
@IBAction func featureRequest(_ sender: UIButton) {
let objectforsecviewcontroller = storyboard?.instantiateViewController(withIdentifier: "SecendViewController") as! SecendViewController
self.navigationController?.pushViewController(objectforsecviewcontroller, animated: true)
}
@IBOutlet weak var getdetalitable: UITableView!
// @IBAction func nextbtn(_ sender: UIButton) {
// let vc = storyboard? .instantiateViewController(withIdentifier: "SecendViewController") as! SecendViewController
// self.navigationController?.pushViewController(vc, animated: true)
//
// }
override func viewDidLoad() {
super.viewDidLoad()
getdata()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func getdata()
{
let dict = [
"name":"shital",
"roll":"one"
]
APIManager.sharedInstance.getuserdetalis(parms: dict, onsuccess: { (arruserdetalis, anystring) in
print(arruserdetalis,anystring)
self.arruserdetalis = arruserdetalis
var str = arruserdetalis[0]
self.getdetalitable.reloadData()
}) { (error1, error2) in
print(error1,error2)
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.arruserdetalis.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:TableViewCell = getdetalitable.dequeueReusableCell(withIdentifier: "TableViewCell") as! TableViewCell
let userdetalis = self.arruserdetalis[indexPath.row]
cell.textLabel?.text = userdetalis.title ?? ""
if(userdetalis.isSelected == true)
{
cell.btnVote.setTitle("Voted", for: .normal)
cell.btnVote.isEnabled = false
}
else {
cell.btnVote.setTitle("Vote your vote", for: .normal)
}
cell.btnVote.tag = indexPath.row
cell.btnVote.addTarget(self, action: #selector(voteButtonPressed(sender:)), for: .touchUpInside)
return cell
}
@objc func voteButtonPressed(sender:UIButton){
let userdetalis = self.arruserdetalis[sender.tag]
self.getdetalitable.reloadData()
let dict = [
"commandtype":"registervote",
"RequestID":userdetalis.id,
"usename":userdetalis.title
] as [String : Any]
APIManager.sharedInstance.voteApi(parms: dict, onsuccess: { (response, anystring) in
print(response,anystring)
self.getdata()
}) { (error1, error2) in
print(error1,error2)
}
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 500.0
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let third = storyboard?.instantiateViewController(withIdentifier: "ThirdViewController") as! ThirdViewController
self.navigationController? .pushViewController(third, animated: true)
}
}
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