I have:
array = [["name": String, "lastName": String],
["name": String, "lastName": String],
["name": String, "lastName": String]]
(a: [Сlass.[String:String]]) -> [Class.SomeStruct] {}
How to make a structure with its properties from this array?
Like this:
struct SomeStruct {
let name: String
let lastName: String
}
You can use map or compactMap to transform your dictionaries into structs.
let array = [["name": "String", "lastName": "String"],
["name": "String", "lastName": "String"],
["name": "String", "lastName": "String"]]
struct SomeStruct {
let name: String
let lastName: String
}
let values = array.compactMap { data -> SomeStruct? in
guard let name = data["name"], let lastName = data["lastName"] else {
return nil
}
return SomeStruct(name: name, lastName: lastName)
}
Note: The compactMap will silently ignore all dictionaries that doesn't contains a name or a lastName key.
Use Codable
// MARK: - SomeStructElement
struct SomeStructElement: Codable, Equatable {
let name: Int?
let lastName: String?
enum CodingKeys: String, CodingKey {
case name = "name"
case lastName = "lastName"
}
}
And then use JSONDecoder:
let someStructArray: Array<SomeStructElement> = try? JSONDecoder().decode(Array<SomeStructElement>.self, from: data) ?? []
Source: Encoding and Decoding Custom Types (Apple developer)
Related
i'm trying to serialize a json but i have an error could someone give me a guide please i'm doing wrong i'm new to swift[enter image description here][1]
let code = "00001"
let firstName = "Joe"
let lastName = "Doe"
let middleName = "Mc."
let age = 100
let weight = 45
let jsonObject: [String: [String:Any]] = [
"code": code, <---- Cannot convert value of type 'String' to expected dictionary value type '[String : Any]'
"attributeMap": [
"first_name": firstName,
"middle_name": middleName,
"last_name": lastName,
"age": age,
"weight": weight
]
]
if let data = try? JSONSerialization.data(withJSONObject: jsonObject, options: .prettyPrinted),
let str = String(data: data, encoding: .utf8) {
print("===> \(str)")
}
--I would like a result like this JSON format
{
"code": "00001",
"attributeMap": {
"first_name": "Joe",
"middle_name": "Mc",
"last_name": "Doe",
"age": "23",
"weight": "home.zul"
}
}
If it repeatable operation I will prefer to use more "swifty" way. Let's define two structs
Person
struct Person: Encodable {
// Keys
enum CodingKeys: String, CodingKey {
case firstName = "first_name"
case middleName = "middle_name"
case lastName = "last_name"
case age
case weight
}
// Properties
let firstName: String
let middleName: String
let lastName: String
let age: Int
let weight: Double
}
The next one
Entity
struct Entity: Encodable {
// Keys
enum CodingKeys: String, CodingKey {
case code
case person = "attributeMap"
}
// Properties
let code: String
let person: Person
}
Usage
let person = Person(
firstName: "Joe",
middleName: "Mc.",
lastName: "Doe",
age: 100,
weight: 45
)
let entity = Entity(
code: "200",
person: person
)
if
let data = try? JSONEncoder().encode(entity),
let json = String(data: data, encoding: .utf8)
{
// Do something
}
Result
{"attributeMap":{"age":100,"last_name":"Doe","middle_name":"Mc.","weight":45,"first_name":"Joe"},"code":"200"}
I have a model that looks like:
public struct Profile {
public let bio: String?
public let company: String
public let createdDate: Date
public let department: String
public let email: String
public let firstName: String
public let coverImageURL: URL?
public let jobTitle: String
public let lastName: String
public let location: String?
public let name: String
public let profileImageURL: URL?
public let roles: [String]
public let isActive: Bool
public let updatedDate: Date?
public let userID: String
public init(
bio: String?, company: String, createdDate: Date, department: String, email: String, firstName: String, coverImageURL: URL?, jobTitle: String,
lastName: String, location: String?, name: String, profileImageURL: URL?, roles: [String], isActive: Bool, updatedDate: Date?, userID: String) {
self.bio = bio
self.company = company
self.createdDate = createdDate
self.department = department
self.email = email
self.firstName = firstName
self.coverImageURL = coverImageURL
self.jobTitle = jobTitle
self.lastName = lastName
self.location = location
self.name = name
self.profileImageURL = profileImageURL
self.roles = roles
self.isActive = isActive
self.updatedDate = updatedDate
self.userID = userID
}
}
extension Profile: Equatable { }
I am trying to create a tuple that represents it as (model: Profile, json: [String: Any])
using the following method -
func makeProfile() -> (model: Profile, json: [String: Any]) {
let updatedDate = Date()
let updatedDateStr = updatedDate.toString(dateFormat: "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX")
let createdDate = Date()
let createdDateStr = createdDate.toString(dateFormat: "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX")
let coverImageURL = makeURL("https://headerUri.com")
let profileImageURL = makeURL("https://pictureUri.com")
let model = Profile(
bio: "Some Bio",
company: "Cool Job INC",
createdDate: createdDate,
department: "Engineering",
email: "name#domain.tld",
firstName: "Anne",
coverImageURL: coverImageURL,
jobTitle: "Test Dummy",
lastName: "Employee",
location: "London",
name: "Anne Employee",
profileImageURL: profileImageURL,
roles: ["ADMIN"],
isActive: true,
updatedDate: updatedDate,
userID: UUID().uuidString
)
let json: [String: Any] = [
"bio": model.bio,
"company": model.company,
"createdDate": createdDateStr,
"department": model.department,
"email": model.email,
"firstName": model.firstName,
"headerUri": model.coverImageURL?.absoluteString,
"jobTitle": model.jobTitle,
"lastName": model.lastName,
"location": model.location,
"name": model.name,
"pictureUri": model.profileImageURL?.absoluteString,
"roles": model.roles,
"isActive": model.isActive,
"updatedDate": updatedDateStr,
"userId": model.userID
].compactMapValues { $0 }
return (model: model, json: json)
}
}
extension Date {
func toString(dateFormat format: String) -> String {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = format
return dateFormatter.string(from: self)
}
}
All of the optional properties are showing a warning Expression implicitly coerced from 'String?' to 'Any'
I have added .compactMapValues { $0 } to the dict but has had no effect.
How can I clear this warning?
You're getting an error because you trying to implicitly coerce an optional value (which could be nil) to Any, which hides that the value could be nil.
compactMapValues doesn't guarantee at compile-time that the value is not nil; all the compiler knows is that something that is an optional (like String?) is now treated as a non-optional Any.
One way you could avoid the error is by providing a default value instead of the optional:
let json: [String: Any] = [
"bio": model.bio ?? ""
// ...
]
Alternatively, you can create a dictionary of: [String, Any?] to assign values to, and then use .compactMapValues, which would give you back non-optional values of Any.
let withOptionals: [String: Any?] = [
"bio": model.bio,
// ...
]
let json: [String, Any] = withOptionals.compactMapValues { $0 }
You're getting the warning because the values are optional when you initialize the dictionary. Your .compactMapValues { $0 } won't help because by then it's "too late".
Instead you could initialize an empty dictionary and add the values 1 by 1.
var json = [String: Any]()
json["bio"] = model.bio
json["company"] = model.company
// all of the other values
json["userId"] = model.userID
How should I model a dictionary property on a Realm object so when encoded to JSON I can get this:
{
"firstName": "John",
"lastName": "Doe",
"favoriteThings": {
"car": "Audi R8",
"fruit": "strawberries",
"tree": "Oak"
}
}
I tried creating a new Object FavoriteThings with 'key' and 'value' properties as I've seen elsewhere...
public class Person: Object {
#objc dynamic var firstName = ""
#objc dynamic var lastName = ""
var favoriteThings = List<FavoriteThings>()
}
But List gives me an array, naturally, when I encode it to JSON. I don't want an array. I'm using Swift Codable.
{
"firstName": "John",
"lastName": "Doe",
"favoriteThings": [
{
"key": "fruit",
"value": "strawberries"
},
{
"key": "tree",
"value": "Oak"
}
],
}
Any pointers appreciated!
Gonzalo
As you know, Lists are encoded into json arrays by default. So, to encode a List into a Dictionary you'll have to implement a custom encode method to do exactly that.
public class FavoriteThings: Object {
#objc dynamic var key = ""
#objc dynamic var value = ""
convenience init(key: String, value: String) {
self.init()
self.key = key
self.value = value
}
}
public class Person: Object, Encodable {
enum CodingKeys: String, CodingKey {
case firstName
case lastName
case favoriteThings
}
#objc dynamic var firstName = ""
#objc dynamic var lastName = ""
let favoriteThings = List<FavoriteThings>()
convenience init(firstName: String, lastName: String, favoriteThings: [FavoriteThings]) {
self.init()
self.firstName = firstName
self.lastName = lastName
self.favoriteThings.append(objectsIn: favoriteThings)
}
public func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(firstName, forKey: .firstName)
try container.encode(lastName, forKey: .lastName)
var favThings: [String: String] = [:]
for thing in favoriteThings {
favThings[thing.key] = thing.value
}
try container.encode(favThings, forKey: .favoriteThings)
}
}
And the usage would be like this:
func testEncode() {
let john = Person(
firstName: "John",
lastName: "Doe",
favoriteThings: [
.init(key: "car", value: "Audi R8"),
.init(key: "fruit", value: "strawberries"),
.init(key: "tree", value: "Oak"),
])
let encoder = JSONEncoder()
let data = try! encoder.encode(john)
if let string = String(data: data, encoding: .utf8) {
print(string)
}
}
Which prints:
{"firstName":"John","favoriteThings":{"car":"Audi R8","fruit":"strawberries","tree":"Oak"},"lastName":"Doe"}
I have a simple model which I defined to decode a struct.
But it is failing at decoding.
Can any one tell me what i am doing wrong?
struct Model: Codable {
let firstName: String
let lastName: String
let age: Int
enum Codingkeys: String, CodingKey {
case firstName = "first_name"
case lastName = "last_name"
case age
}
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let session = URLSession.shared
let url = URL(string: "https://learnappmaking.com/ex/users.json")!
let task = session.dataTask(with: url) { (data, response, error) in
let decoder = JSONDecoder()
let d = try! decoder.decode([Model].self, from: data!) //fails here
print(d)
}
task.resume()
}
}
I double checked to see if the json was correct, but it still fails to decode.
Error shown
Thread 5: Fatal error: 'try!' expression unexpectedly raised an error:
Swift.DecodingError.keyNotFound(CodingKeys(stringValue: "firstName",
intValue: nil), Swift.DecodingError.Context(codingPath:
[_JSONKey(stringValue: "Index 0", intValue: 0)], debugDescription: "No
value associated with key CodingKeys(stringValue: \"firstName\",
intValue: nil) (\"firstName\").", underlyingError: nil))
It keeps searching for firstName but i specifically have a enum to check for first_name.
This is the JSON Payload
[
{
"first_name": "Ford",
"last_name": "Prefect",
"age": 5000
},
{
"first_name": "Zaphod",
"last_name": "Beeblebrox",
"age": 999
},
{
"first_name": "Arthur",
"last_name": "Dent",
"age": 42
},
{
"first_name": "Trillian",
"last_name": "Astra",
"age": 1234
}
]
I know I can add decoder.keyDecodingStrategy = .convertFromSnakeCase but I want to know why the existing code is not working?
The code is correct, but apparently there is some problem with your model (although convertFromSnakeCase does work)
I retyped the struct and the error went away. Please copy and paste this
struct Model : Decodable {
let firstName : String
let lastName : String
let age : Int
private enum CodingKeys : String, CodingKey { case firstName = "first_name", lastName = "last_name", age }
}
Some of the values are optional, to be safe make all let as optional, It will work for sure.
struct Model: Codable {
let firstName: String?
let lastName: String?
let age: Int?
enum Codingkeys: String, CodingKey {
case firstName = "first_name"
case lastName = "last_name"
case age
}
}
How does the Swift 4 Decodable protocol cope with a dictionary containing a key whose name is not known until runtime? For example:
[
{
"categoryName": "Trending",
"Trending": [
{
"category": "Trending",
"trailerPrice": "",
"isFavourit": null,
"isWatchlist": null
}
]
},
{
"categoryName": "Comedy",
"Comedy": [
{
"category": "Comedy",
"trailerPrice": "",
"isFavourit": null,
"isWatchlist": null
}
]
}
]
Here we have an array of dictionaries; the first has keys categoryName and Trending, while the second has keys categoryName and Comedy. The value of the categoryName key tells me the name of the second key. How do I express that using Decodable?
The key is in how you define the CodingKeys property. While it's most commonly an enum it can be anything that conforms to the CodingKey protocol. And to make dynamic keys, you can call a static function:
struct Category: Decodable {
struct Detail: Decodable {
var category: String
var trailerPrice: String
var isFavorite: Bool?
var isWatchlist: Bool?
}
var name: String
var detail: Detail
private struct CodingKeys: CodingKey {
var intValue: Int?
var stringValue: String
init?(intValue: Int) { self.intValue = intValue; self.stringValue = "\(intValue)" }
init?(stringValue: String) { self.stringValue = stringValue }
static let name = CodingKeys.make(key: "categoryName")
static func make(key: String) -> CodingKeys {
return CodingKeys(stringValue: key)!
}
}
init(from coder: Decoder) throws {
let container = try coder.container(keyedBy: CodingKeys.self)
self.name = try container.decode(String.self, forKey: .name)
self.detail = try container.decode([Detail].self, forKey: .make(key: name)).first!
}
}
Usage:
let jsonData = """
[
{
"categoryName": "Trending",
"Trending": [
{
"category": "Trending",
"trailerPrice": "",
"isFavourite": null,
"isWatchlist": null
}
]
},
{
"categoryName": "Comedy",
"Comedy": [
{
"category": "Comedy",
"trailerPrice": "",
"isFavourite": null,
"isWatchlist": null
}
]
}
]
""".data(using: .utf8)!
let categories = try! JSONDecoder().decode([Category].self, from: jsonData)
(I changed isFavourit in the JSON to isFavourite since I thought it was a mispelling. It's easy enough to adapt the code if that's not the case)
You can write a custom struct that functions as a CodingKeys object, and initialize it with a string such that it extracts the key you specified:
private struct CK : CodingKey {
var stringValue: String
init?(stringValue: String) {
self.stringValue = stringValue
}
var intValue: Int?
init?(intValue: Int) {
return nil
}
}
Thus, once you know what the desired key is, you can say (in the init(from:) override:
let key = // whatever the key name turns out to be
let con2 = try! decoder.container(keyedBy: CK.self)
self.unknown = try! con2.decode([Inner].self, forKey: CK(stringValue:key)!)
So what I ended up doing is making two containers from the decoder — one using the standard CodingKeys enum to extract the value of the "categoryName" key, and another using the CK struct to extract the value of the key whose name we just learned:
init(from decoder: Decoder) throws {
let con = try! decoder.container(keyedBy: CodingKeys.self)
self.categoryName = try! con.decode(String.self, forKey:.categoryName)
let key = self.categoryName
let con2 = try! decoder.container(keyedBy: CK.self)
self.unknown = try! con2.decode([Inner].self, forKey: CK(stringValue:key)!)
}
Here, then, is my entire Decodable struct:
struct ResponseData : Codable {
let categoryName : String
let unknown : [Inner]
struct Inner : Codable {
let category : String
let trailerPrice : String
let isFavourit : String?
let isWatchList : String?
}
private enum CodingKeys : String, CodingKey {
case categoryName
}
private struct CK : CodingKey {
var stringValue: String
init?(stringValue: String) {
self.stringValue = stringValue
}
var intValue: Int?
init?(intValue: Int) {
return nil
}
}
init(from decoder: Decoder) throws {
let con = try! decoder.container(keyedBy: CodingKeys.self)
self.categoryName = try! con.decode(String.self, forKey:.categoryName)
let key = self.categoryName
let con2 = try! decoder.container(keyedBy: CK.self)
self.unknown = try! con2.decode([Inner].self, forKey: CK(stringValue:key)!)
}
}
And here's the test bed:
let json = """
[
{
"categoryName": "Trending",
"Trending": [
{
"category": "Trending",
"trailerPrice": "",
"isFavourit": null,
"isWatchlist": null
}
]
},
{
"categoryName": "Comedy",
"Comedy": [
{
"category": "Comedy",
"trailerPrice": "",
"isFavourit": null,
"isWatchlist": null
}
]
}
]
"""
let myjson = try! JSONDecoder().decode(
[ResponseData].self,
from: json.data(using: .utf8)!)
print(myjson)
And here's the output of the print statement, proving that we've populated our structs correctly:
[JustPlaying.ResponseData(
categoryName: "Trending",
unknown: [JustPlaying.ResponseData.Inner(
category: "Trending",
trailerPrice: "",
isFavourit: nil,
isWatchList: nil)]),
JustPlaying.ResponseData(
categoryName: "Comedy",
unknown: [JustPlaying.ResponseData.Inner(
category: "Comedy",
trailerPrice: "",
isFavourit: nil,
isWatchList: nil)])
]
Of course in real life we'd have some error-handling, no doubt!
EDIT Later I realized (in part thanks to CodeDifferent's answer) that I didn't need two containers; I can eliminate the CodingKeys enum, and my CK struct can do all the work! It is a general purpose key-maker:
init(from decoder: Decoder) throws {
let con = try! decoder.container(keyedBy: CK.self)
self.categoryName = try! con.decode(String.self, forKey:CK(stringValue:"categoryName")!)
let key = self.categoryName
self.unknown = try! con.decode([Inner].self, forKey: CK(stringValue:key)!)
}
Here's what I eventually came up for this json:
let json = """
{
"BTC_BCN":{
"last":"0.00000057",
"percentChange":"0.03636363",
"baseVolume":"47.08463318"
},
"BTC_BELA":{
"last":"0.00001281",
"percentChange":"0.07376362",
"baseVolume":"5.46595029"
}
}
""".data(using: .utf8)!
We make such a structure:
struct Pair {
let name: String
let details: Details
struct Details: Codable {
let last, percentChange, baseVolume: String
}
}
then decode:
if let pairsDictionary = try? JSONDecoder().decode([String: Pair.Details].self, from: json) {
var pairs: [Pair] = []
for (name, details) in pairsDictionary {
let pair = Pair(name: name, details: details)
pairs.append(pair)
}
print(pairs)
}
It is also possible to call not pair.details.baseVolume, but pair.baseVolume:
struct Pair {
......
var baseVolume: String { return details.baseVolume }
......
Or write custom init:
struct Pair {
.....
let baseVolume: String
init(name: String, details: Details) {
self.baseVolume = details.baseVolume
......