Json Decode

ContentView.swift

//
//  ContentView.swift
//  JongjuAR
//
//  Created by 전민정 on 6/6/22.
//

import SwiftUI

struct ContentView: View {
    
    @ObservedObject var datas = ReadData()
    
    var body: some View {
        NavigationView {
            List(datas.jongjus) { jongju in
                Section(header: Text(jongju.name)) {
                    ForEach(jongju.routes) { route in
                        NavigationLink(destination: DownloadGPXView(route: route)) {
                            Text(route.name)
                        }
                    }
                    
                    
                }
            }
        }
        
    }
}

struct DownloadGPXView: View {
    var route: Route
    
    init(route: Route) {
        self.route = route
    }
    
    var body: some View {
        List {
            ForEach(route.courses) { course in
                Text(course.name)
            }
        }
    }
}

class ReadData: ObservableObject {
    @Published var jongjus = [Jongju]()
    
    init() {
        loadData()
    }
    
    func loadData() {
        guard let url = Bundle.main.url(forResource: "Backdu", withExtension: "json") else {
            print("json not found...")
            return
        }
        let data = try? Data(contentsOf: url)
        do {
            let jongjus = try JSONDecoder().decode([Jongju].self, from: data!)
            self.jongjus = jongjus
        } catch {
            print(error)
        }
       
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Model.swift

//
//  Model.swift
//  JongjuAR
//
//  Created by 전민정 on 6/8/22.
//

import Foundation

struct Course : Codable, Identifiable {
    enum CodingKeys: CodingKey {
        case num
        case name
        case mmap
        case gpx
    }
    var id = UUID()
    var num: Int
    var name: String
    var mmap: String
    var gpx: String
}

struct Route : Codable, Identifiable {
    enum CodingKeys: CodingKey {
        case num
        case name
        case courseType
        case courseCnt
        case courses
    }
    var id = UUID()
    var num: Int
    var name: String
    var courseType: String
    var courseCnt: Int
    var courses: [Course]
    
    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        num = try values.decode(Int.self, forKey: .num)
        name = try values.decode(String.self, forKey: .name)
        courseType = try values.decode(String.self, forKey: .courseType)
        courseCnt = try values.decode(Int.self, forKey: .courseCnt)
        courses = try values.decode([Course].self, forKey: .courses)
    }
}

struct Jongju : Identifiable, Codable {
    enum CodingKeys: CodingKey {
        case name
        case routes
    }
    var id = UUID()
    var name: String    // 백두대간
    var routes: [Route]
}

Backdu.json 일부

[{
    "name": "백두대간",
    "routes": [
        {
            "num": 1,
            "name": "지리산권",
            "courseType": "종주",
            "courseCnt": 7,
            "courses": [
                {
                    "num": 1,
                    "name": "천왕봉-세석산장",
                    "mmap": "",
                    "gpx": "백두대간_지리산권_종주_1코스.gpx"
                },
                {
                    "num": 2,
                    "name": "세석산장-토끼봉",
                    "mmap": "",
                    "gpx": "백두대간_지리산권_종주_2코스.gpx"
                },
                {
                    "num": 3,
                    "name": "토끼봉-헬기장",
                    "mmap": "",
                    "gpx": "백두대간_지리산권_종주_3코스.gpx"
                },

References

https://developer.mozilla.org/ko/docs/Learn/JavaScript/Objects/JSON

JSON으로 작업하기 - Web 개발 학습하기 | MDN

https://jinnify.tistory.com/71

[Swift] Codable - Decoding 방법

https://stackoverflow.com/questions/44580719/how-do-i-make-an-enum-decodable-in-swift-4/44582674#44582674

How do I make an enum Decodable in swift 4?

https://discourse.codershigh.com/t/codable/454

Codable 관련 질문 드립니다

https://medium.com/@nutanbhogendrasharma/read-json-data-from-file-system-in-swiftui-d054662000e

Read JSON Data From File System in SwiftUI Mobile App

https://www.hohyeonmoon.com/blog/swiftui-tutorial-navigation/

SwiftUI NavigationView 사용하기 | Hohyeon Moon