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json - Swift JSON解码器不同类型

问题描述

我有这两个 JSON 对象

[ 
{"name": "Popular Movies", 
"description": "Basic movie description", 
"type": "movies", 
"items": [ { "id": 15, "name": "Sample movie", "movieSPT": ""}]
},
{"name": "Popular TV Shows", 
"description": "Basic shows description", 
"type": "tvshows", 
"items": [ { "id": 15, "name": "Sample show", "showSPT": ""}]
}
]

然后我为节目和电影创建了两个可解码结构：

struct Movie: Decodable {
    let id: Int
    let name: String
    let movieSPT: String
}

struct TVShow: Decodable {
    let id: Int
    let name: String
    let showSPT: String
}

那么，当我为主要响应创建对象时，创建项目数组的最佳方法是什么取决于类型值？我知道我可以为某些独特的结构创建带有可选属性的 showSPT 和 movieSPT，但这是正确的方法吗？另外，如果这两个模型有很多属性，combine struct 就会太大。

struct Blocks : Decodable {
    let name: String
    let description: String
    let type: String
    let items: [Movie] or [Show] based on type????
}

标签： jsonswiftparsing

解决方案

有几个解决方案。其中之一是具有关联类型的枚举

let jsonString = """
[{"name": "Popular Movies", "description": "Basic movie description", "type": "movies",
    "items": [ { "id": 15, "name": "Sample movie", "movieSPT": ""}]
},
{"name": "Popular TV Shows", "description": "Basic shows description", "type": "tvshows",
"items": [ { "id": 15, "name": "Sample show", "showSPT": ""}]
}
]
"""
let data = Data(jsonString.utf8)


struct Movie : Decodable {
    let id: Int
    let name, movieSPT: String
}

struct TVShow : Decodable {
    let id: Int
    let name, showSPT: String
}

enum MediaType {
    case movie([Movie]), tvShow([TVShow])
}

struct Media : Decodable {
    let name : String
    let description : String
    let items : MediaType

    private enum CodingKeys : String, CodingKey { case name, description, type, items }

    init(from decoder : Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.name = try container.decode(String.self, forKey: .name)
        self.description = try container.decode(String.self, forKey: .description)
        let type = try container.decode(String.self, forKey: .type)
        if type == "movies" {
            let movieData = try container.decode([Movie].self, forKey: .items)
            items = .movie(movieData)
        } else { // add better error handling
            let showData = try container.decode([TVShow].self, forKey: .items)
            items = .tvShow(showData)
        }

    }
}

do {
    let result = try JSONDecoder().decode([Media].self, from: data)
    print(result)
} catch {
    print(error)
}

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