Question

我尝试动态编程一个切换开关，以在我的SwiftUI项目中显示一个较短的列表。

我使用的JSON文件是here。
我的项目在GitHub上。

我像这样编写切换器，但是当我打开它时，它不会显示正确的列表。目标是将JSON isShow属性链接到toggle属性。拨动为OFF时，将显示完整列表；拨动为ON时，仅显示isShow = FALSE列表。

struct Movie: Decodable, Encodable, Identifiable {
public var id: Int
public var nom: String
public var idL: String
public var note: Int
public var isShow: Bool

enum CodingKeys: String, CodingKey {
       case id = "id"
       case nom = "nom"
       case idL = "idL"
       case note = "note"
       case isShow = "isShow"
    }
}

电影结构是

public class MovieFetcher: ObservableObject {
func save(movies: [Movie]) {

    OperationQueue().addOperation {

        do {
            let encoded = try JSONEncoder().encode(movies)
            let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)

            do {
                try encoded.write(to: url[0].appendingPathComponent("movies"))
                print("saved to ", url[0])
            } catch {
                print(error)
            }

        } catch {
            print(error)
        }
    }
}

func load(completion: @escaping (([Movie]?) -> () )) {

    let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)

    do {
        if let data = try? Data(contentsOf: urls[0].appendingPathComponent("movies")) {

            let decodedLists = try JSONDecoder().decode([Movie].self, from: data as Data)
            DispatchQueue.main.async {
                completion(decodedLists)
            }


        } else {
            loadFromJson(completion: completion)
        }
    } catch {
        print(error)
        completion(nil)
    }
}

func loadFromJson(completion: @escaping (([Movie]?) -> () )) {

    let url = URL(string: "https://gist.githubusercontent.com/thomjlg/0782e9e8e27c346af3600bff9923f294/raw/9705fb0c6b40eae59578755b86e331bea257972b/films2.json")!

    URLSession.shared.dataTask(with: url) {(data,response,error) in
        do {
            if let d = data {
                let decodedLists = try JSONDecoder().decode([Movie].self, from: d)
                DispatchQueue.main.async {
                    completion(decodedLists)
                }
            }else {
                print("No Data")
                completion(nil)
            }
        } catch {
            print ("Error")
            completion(nil)
        }

    }.resume()
}
}

json提取程序是：

let str = "{'name':'joe', 'text':\"that's amazing\", 'registered':True, 'height':193, 'related':{'foo':'bar', 'some':'thing'}}"

有人知道如何更正我的代码吗？
谢谢

Answer 1

如果我正确理解您的问题，则需要调整过滤器。如果正确，请尝试使用以下过滤器：

ForEach(0..<self.userData.movies.filter{ self.showShowOnly ? $0.isShow == !self.showShowOnly : true }.count, id: \.self)

当self.showShowOnly = false时，这将为您提供完整列表。

当self.showShowOnly = true时，将为您提供所有带有“ isShow = false”的电影。

Answer 2

过滤器代码有效。请注意，在323部电影中，只有1部电影的“ isShow” = true。

  "nom":"Ratatouille",
        "id":217,
        "idL":"R",
        "note":0,
        "isShow":true

问题是在ForEach循环中使用“ movieIndex”的方式。 “ movieIndex”是指过滤后的self.userData.movies列表的索引。这个“电影索引” 不应在self.userData.movies [movieIndex]中使用。

要解决此问题，请执行以下操作：

                    ForEach(self.userData.movies.filter{ self.showShowOnly ? $0.isShow == !self.showShowOnly : true }) { movie in
                        VStack (alignment: .leading) {
                            NavigationLink(destination: ContentView(movie: movie)) {
                                Text(movie.nom)
                            }
                        }
                    }

尝试一下，让我知道是否可行。

编辑：尝试将此类用于Movie而不是struct

open class Movie: Codable, Identifiable, Equatable, Hashable, ObservableObject {

@Published public var id: Int
@Published public var nom: String
@Published public var idL: String
@Published public var note: Int
@Published public var isShow: Bool

enum CodingKeys: String, CodingKey {
    case id = "id"
    case nom = "nom"
    case idL = "idL"
    case note = "note"
    case isShow = "isShow"
}

public static func == (lhs: Movie, rhs: Movie) -> Bool {
    lhs.id == rhs.id
}

public func hash(into hasher: inout Hasher) {
    hasher.combine(id)
}

public init(id: Int, nom: String, idL: String, note: Int, isShow: Bool) {
    self.id = id
    self.nom = nom
    self.idL = idL
    self.note = note
    self.isShow = isShow
}

public init() {
    self.id = UUID().hashValue
    self.nom = ""
    self.idL = ""
    self.note = 0
    self.isShow = false
}

public required init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    self.id = try container.decode(Int.self, forKey: .id)
    self.nom = try container.decode(String.self, forKey: .nom)
    self.idL = try container.decode(String.self, forKey: .idL)
    self.note = try container.decode(Int.self, forKey: .note)
    self.isShow = try container.decode(Bool.self, forKey: .isShow)
}

public func encode(to encoder: Encoder) throws {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(id, forKey: .id)
    try container.encode(nom, forKey: .nom)
    try container.encode(idL, forKey: .idL)
    try container.encode(note, forKey: .note)
    try container.encode(isShow, forKey: .isShow)
}
}

请注意，您必须在ContentView中将“ @Binding var movie：Movie”更改为“ @ObservedObject var movie：Movie”，并调整“ ContentView_Previews”。

如何在切换SwiftUI中使用json属性？

2 个答案: