I'm trying to create a weather application. I followed a tutorial about JSON and Swift 4 Decodable, I followed the tutorial and it worked. The problem is that when I'm trying to put my own URL to make a request, it won't work.
This is my code:
class MainVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
let jsonUrlString: String = "https://api.darksky.net/forecast/APIKEY/37.8267,-122.4233"
private func getForecast(){
guard let url = URL(string: jsonUrlString) else { return }
URLSession.shared.dataTask(with: url) { (data, response, err) in
guard let data = data else { return }
do{
let weatherForecast = try JSONDecoder().decode(Weather.self, from: data)
print(weatherForecast)
}catch _ as NSError{
}
}.resume()
}
}
Error Log:
Error Domain=NSCocoaErrorDomain Code=4864 "Expected to decode Array<Any> but found a dictionary instead." UserInfo={NSCodingPath=(
), NSDebugDescription=Expected to decode Array<Any> but found a dictionary instead.}
How can I parse this https://darksky.net/dev/docs#forecast-request ? I only need the few things from the Daily sections but It seems like an array inside an array to me.
It looks like your Weather struct is built up incorrectly. It should looks something like this:
struct DataItem: Codable {
var summary: String
var uvIndex: Int
}
struct Info: Codable {
var summary: String
var icon: String
var data: [DataItem]
}
struct Weather: Codable {
var daily: Info
var hourly: Info
var timezone: String
}
I've left quite a few items out, but this should help you to get started.
Related
I know there are already some articles regarding this issue, but I could not find anything related to my JSON.
This is how my JSON likes like:
{
"message": {
"affenpinscher": [],
"african": [],
"airedale": [],
"akita": [],
"appenzeller": [],
"australian": [
"shepherd"
],
"basenji": []
},
"status: "succes"
}
So, if I understand it correctly it is dictionary because it starts with {, but what are the things inside the "message"?
This is my Dog.swift class where I am re-writing the JSON, but I am not sure if it is correct:
class Dog: Decodable, Identifiable {
var message: Message?
var status: String?
}
struct Message: Decodable {
var affenpinscher: [String:[String]]?
var african: [String]?
var airedale: [String]?
var akita: [String]?
var appenzeller: [String]?
var australian: [String]?
var basenji: [String]?
}
As you can see in the first value I was trying to play with data types, but no success.
I am decoding and parsing JSON here:
class ContentModel: ObservableObject {
#Published var dogs = Message()
init() {
getDogs()
}
func getDogs(){
// Create URL
let urlString = Constants.apiUrl
let url = URL(string: urlString)
if let url = url {
// Create URL request
var request = URLRequest(url: url, cachePolicy: .reloadIgnoringLocalCacheData, timeoutInterval: 10)
request.httpMethod = "GET"
// Get URLSession
let session = URLSession.shared
// Create Data Task
let dataTask = session.dataTask(with: request) { (data, response, error) in
// Check that there is not an error
if error == nil {
do {
// Parse JSON
let decoder = JSONDecoder()
let result = try decoder.decode(Dog.self, from: data!)
print(result)
// Assign result to the dogs property
DispatchQueue.main.async {
self.dogs = result.message!
}
} catch {
print(error)
}
}
}
// Start the Data Task
dataTask.resume()
}
}
}
And here I would love to iterate through it eventually, which I also have no idea how to do it:
struct ContentView: View {
#EnvironmentObject var model: ContentModel
var body: some View {
NavigationView {
ScrollView {
LazyVStack {
if model.dogs != nil {
// ForEach(Array(model.dogs.keys), id: \.self) { d in
// Text(d)
// }
}
}
.navigationTitle("All Dogs")
}
}
}
}
What can I try next to resolve this?
First of all don't use classes for a JSON model and to conform to Identifiable you have to add an id property and CodingKeys if there is no key id in the JSON.
My suggestion is to map the unhandy [String: [String]] dictionary to an array of an extra struct
I renamed Dog as Response and named the extra struct Dog
struct Dog {
let name : String
let types : [String]
}
struct Response: Decodable, Identifiable {
private enum CodingKeys: String, CodingKey { case message, status }
let id = UUID()
let dogs: [Dog]
let status: String
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
status = try container.decode(String.self, forKey: .status)
let message = try container.decode([String:[String]].self, forKey: .message)
dogs = message.map(Dog.init).sorted{$0.name < $1.name}
}
}
In the model declare
#Published var dogs = [Dog]()
and decode
let result = try decoder.decode(Response.self, from: data!)
print(result)
// Assign result to the dogs property
DispatchQueue.main.async {
self.dogs = result.dogs
}
The dogs array can be displayed seamlessly in a List
PS: Actually appenzeller is supposed to be
"appenzeller": ["sennenhund"],
or correctly in English
"appenzell": ["mountain dog"],
😉😉😉
Using the native Swift approach that #vadian answered is a much lighter weight solution, but if you work with JSON often I'd recommend using SwiftyJSON.
You can parse the URL data task response into a Swifty json object like so:
import SwiftyJSON
guard let data = data, let json = try? JSON(data: data) else {
return
}
// Make sure the json fetch was successful
if json["status"].stringValue != "success" {
return
}
Then you can access the message object safely without the verbosity of using Decodable. Here the message is parsed into an array of dog structs:
struct Dog {
let name : String
let types : [String]
}
var dogs: [Dog] = []
/// Load the docs into an array
for (name, typesJson) in json["message"].dictionaryValue {
dogs.append(Dog(name: name, types: typesJson.arrayValue.map { $0.stringValue }))
}
print("dogs", dogs)
I'm making an Xcode project involving an API call. When I make the call and try to access a certain part of the JSON file I can't seem to get it to work. When I try to print the data I fetch it just prints a blank row. I'm guessing I've done something wrong when I'm trying to accessing the data and pass it onto the travelTimevariable. You can find the JSON data by following the URL string in the code below.
I also get this message in my Xcode console and I don't know why and if it's related to the problem.
nw_protocol_get_quic_image_block_invoke dlopen libquic failed
I'm a beginner at Swift so I've been following tutorials online, but I can't find what I have done wrong in my code.
import SwiftUI
struct ContentView: View {
#State var travelTime = String()
var body: some View {
Text("Time:\(travelTime)")
Button("FetchAPI"){FetchAPI()}
}
func FetchAPI() {
let url = URL(string: "http://api.sl.se/api2/TravelplannerV3_1/trip.xml?key=40892db48b394d3a86b2439f9f3800fd&originExtId=300101416&destExtId=300101426&Date=2021-04-15&Time=08:00&searchForArrival=1")
URLSession.shared.dataTask(with: url!) {data, response, error in
if let data = data {
if let decodedJson = try? JSONDecoder().decode(JSONStructure.self, from: data) {
self.travelTime = decodedJson.Trip[0].LegList.Leg[0].Origin.time
}
}
}.resume()
print(self.travelTime)
}
}
struct JSONStructure: Decodable {
let Trip: [TripStructure]
}
struct TripStructure: Decodable {
let LegList: LegListStructure
}
struct LegListStructure: Decodable {
let Leg: [LegStructure]
}
struct LegStructure: Decodable {
let Origin: OriginStructure
}
struct OriginStructure: Decodable {
let time: String
}
I have been trying to get this code to work for like 6 hours. I get the error: "failed to convert The data couldn’t be read because it is missing." I don't know while the File is missing is there something wrong in my models(structs). Do I need to write a struct for very json dictionary? Currently I have only made those JSON dictionaries to a struct, which I actually need. The full JSON file can be found at https://api.met.no/weatherapi/sunrise/2.0/.json?lat=40.7127&lon=-74.0059&date=2020-12-22&offset=-05:00 . I want to be able to print the time of the sunrise, sunset and solar noon as well as the elevation of the sun at solar noon. It's currently 1 am and I am desperate. Good Night!
class ViewController: NSViewController {
#IBOutlet weak var sunriseField: NSTextField!
#IBOutlet weak var sunsetField: NSTextField!
#IBOutlet weak var daylengthField: NSTextField!
override func viewDidLoad() {
super.viewDidLoad()
let url = "https://api.met.no/weatherapi/sunrise/2.0/.json?lat=40.7127&lon=-74.0059&date=2020-12-22&offset=-05:00"
getData(from: url)
// Do any additional setup after loading the view.
}
private func getData(from url: String) {
let task = URLSession.shared.dataTask(with: URL(string: url)!, completionHandler: {data, response, error in
guard let data = data, error == nil else {
print("something went wrong")
return
}
var result: MyTime?
do {
result = try JSONDecoder().decode(MyTime.self, from: data)
}
catch {
print("failed to convert \(error.localizedDescription)")
}
guard let json = result else {
return
}
let sunrise1 = json.sunrise.time
DispatchQueue.main.async { [weak self] in
self?.sunriseField.stringValue = sunrise1
}
print(json)
})
task.resume()
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
}
struct MyData : Codable {
let location : Location
let meta : Meta
}
struct MyTime : Codable {
let solarnoon : Solarnoon
let sunset : Sunset
let sunrise : Sunrise
}
struct Location : Codable {
let height : String
let time : [MyTime]
let longitude : String
let latitude : String
}
struct Meta : Codable {
let licenseurl : String
}
struct Solarnoon : Codable {
let desc : String
let time : String
let elevation : String
}
struct Sunrise : Codable {
let desc : String
let time : String
}
struct Sunset : Codable {
let time : String
let desc : String
}
You don't really have a SwiftUI class, but that is a different question. I am going to work on fixing getData(). I have tried to comment it extensively, but let me know if you have any questions.
private func getData(from url: String) {
// Personally I like converting the string to a URL to unwrap it and make sure it is valid:
guard let url = URL(string: urlString) else {
print("Bad URL: \(urlString)")
return
}
let config = URLSessionConfiguration.default
// This will hold the request until you have internet
config.waitsForConnectivity = true
URLSession.shared.dataTask(with: url) { data, response, error in
// A check for a bad response
guard let httpResponse = response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
print("Bad Server Response")
return
}
if let data = data {
// You can print(data) here that will shown you the number of bytes returned for debugging.
//This work needs to be done on the main thread:
DispatchQueue.main.async {
let decoder = JSONDecoder()
if let json = try? decoder.decode(MetDecoder.self, from: data){
print(json)
//At this point, you have your data in a struct
self.sunriseTime = json.dailyData?.solarData?.first?.sunrise?.time
}
}
}
}
.resume()
}
With regard to your structs, you only need them for the data you are trying to parse. If you don't need it, don't worry about it. I would make this a separate class named MetDecoder or something that makes sense to you and indicates the decoder for your JSON. You will also note that I changed the names of some of the variables. You can do that so long as you use a CodingKeys enum to translate your JSON to your struct as in the case of dailyData = "location", etc. This is ugly JSON, and I am not sure why the Met decided everything should be a string, but this decoder is tested and it works:
import Foundation
// MARK: - MetDecoder
struct MetDecoder: Codable {
let dailyData: DailyData?
enum CodingKeys: String, CodingKey {
case dailyData = "location"
}
}
// MARK: - Location
struct DailyData: Codable {
let solarData: [SolarData]?
enum CodingKeys: String, CodingKey {
case solarData = "time"
}
}
// MARK: - Time
struct SolarData: Codable {
let sunrise, sunset: RiseSet?
let solarnoon: Position?
let date: String?
enum CodingKeys: String, CodingKey {
case sunrise, sunset, solarnoon, date
}
}
// MARK: - HighMoon
struct Position: Codable {
let time: String?
let desc, elevation, azimuth: String?
}
// MARK: - Moonrise
struct RiseSet: Codable {
let time: String?
let desc: String?
}
You should see what the National Weather Service does to us in the US to get the JSON. Lastly, when working on JSON I find the following pages VERY helpful:
JSON Formatter & Validator which will help you parse out the wall of text that gets returned in a browser, and
quicktype which will parse JSON into a programming language like Swift. I will warn you that the parsing can give some very ugly structs in Swift, but it gives you a nice start. I used both sites for this answer.
Apple's new framework, Combine, helps to simplify the code needed for async fetch requests. I have used the MetDecoder in #Yrb's response above (you can accept his answer) and altered the getData() function. Just make sure you import Combine at the top.
import Combine
var sunriseTime: String?
var sunsetTime: String?
var solarNoonTime: String?
var solarNoonElevation: String?
func getData() {
let url = URL(string: "https://api.met.no/weatherapi/sunrise/2.0/.json?lat=40.7127&lon=-74.0059&date=2020-12-22&offset=-05:00")!
URLSession.shared.dataTaskPublisher(for: url)
// fetch on background thread
.subscribe(on: DispatchQueue.global(qos: .background))
// recieve response on main thread
.receive(on: DispatchQueue.main)
// ensure there is data
.tryMap { (data, response) in
guard
let httpResponse = response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
throw URLError(.badServerResponse)
}
return data
}
// decode JSON data to MetDecoder
.decode(type: MetDecoder.self, decoder: JSONDecoder())
// Handle results
.sink { (result) in
// will return success or failure
print("completion: \(result)")
} receiveValue: { (value) in
// if success, will return MetDecoder
// here you can update your view
print("value: \(value)")
if let solarData = value.dailyData?.solarData?.first {
self.sunriseTime = solarData.sunrise?.time
self.sunsetTime = solarData.sunset?.time
self.solarNoonTime = solarData.solarnoon?.time
self.solarNoonElevation = solarData.solarnoon?.elevation
}
}
// After recieving response, the URLSession is no longer needed & we can cancel the publisher
.cancel()
}
from the json data (2nd entry), looks like you need at least:
struct MyTime : Codable {
let solarnoon : Solarnoon?
let sunset : Sunset?
let sunrise : Sunrise?
}
and you need:
var result: MyData?
do {
result = try JSONDecoder().decode(MyData.self, from: data)
}
catch {
print("----> error failed to convert \(error)")
}
I am trying to use the open weathermap.org api to return the "main" key in JSON. For some reason I keep getting caught up in my error around "failed to convert". I'm not exactly sure why I am failing to convert the JSON anyone have any ideas? Thank you.
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
let url = "https://api.openweathermap.org/data/2.5/weather?zip=10514&appid=#####################"
getData(from: url)
}
struct Response: Codable {
let weather: MyResult
}
struct MyResult: Codable {
let main: String
}
Below is the function being called to change access the JSON.
private func getData(from url:String) {
URLSession.shared.dataTask(with: URL(string:url)!, completionHandler: {
data, response, error in
guard let data = data, error == nil else {
print("Something went wrong")
return
}
// have data
var result: Response?
do {
result = try JSONDecoder().decode(Response.self, from: data)
} catch {
print("failed to convert")
}
guard let json = result else {
return
}
print(json.weather.main)
}).resume()
}
EDIT: This is what the json pulls up. Am I creating the structs incorrectly? if so how should I do it properly? thank you
{"coord":{"lon":-73.73,"lat":41.2},"weather":[{"id":802,"main":"Clouds","description":"scattered clouds","icon":"03n"}],"base":"stations","main":{"temp":291.67,"feels_like":288.73,"temp_min":290.93,"temp_max":292.59,"pressure":1024,"humidity":72},"visibility":10000,"wind":{"speed":5.7,"deg":130},"clouds":{"all":40},"dt":1594956028,"sys":{"type":1,"id":4403,"country":"US","sunrise":1594892168,"sunset":1594945530},"timezone":-14400,"id":0,"name":"Mount Kisco","cod":200}
In the JSON response, the property weather is an array:
{..., weather: [{...}] }
but in your model it expects a MyResult type. Change it to expect an array of [MyResult]:
struct Response: Codable {
let weather: [MyResult]
}
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
//API Key: 5ca10b2d20a545099a108a3aeceb329c
//url: https://newsapi.org/v2/top-headlines?country=us&apiKey=5ca10b2d20a545099a108a3aeceb329c
// model
struct Source: Decodable {
var id: String
var name: String
}
struct Articles: Decodable {
var source: Source
var author: String
var title: String
var description: String
var url: String
var urlToImage: String
var publishedAt: String
var content: String
}
struct JSONDescription: Decodable {
var status: String
var totalResults: Int
var articles: Articles
}
guard let url = URL(string: "https://newsapi.org/v2/top-headlines?country=us&apiKey=5ca10b2d20a545099a108a3aeceb329c") else { return }
URLSession.shared.dataTask(with: url) { data, response, error in
guard let data = data else { return }
//let dataAsString = String(data: data, encoding: .utf8)
// print(dataAsString)
do {
let jsonDescription = try JSONDecoder().decode(JSONDescription.self, from: data)
print(jsonDescription.totalResults)
}
catch let jsonError {
print("Json Error:", jsonError)
}
}.resume()
}
}
What I expected to see was the JSON data returned here: https://newsapi.org/v2/top-headlines?country=us&apiKey=5ca10b2d20a545099a108a3aeceb329c
You can put it into this formatter to make is readable: https://jsonformatter.curiousconcept.com
I thought I did everything correctly. Have I built my model wrong? I'm not sure how to fix this error.
So, with the help of the error returned, and looking at the data, it seems that "articles" is an array.
Here's what I'd try:
Rename your Articles struct to Article
Change JSONDescription's articles property from Articles to [Article]
I didn't notice any other errors in the data mapping, but hopefully this gets you closer.