如何使用Swift Decodable属性解码嵌套数组的嵌套字典？

Question

我需要用swift4解析的实际JSON是，

{
    "class": {
        "semester1": [
            {
                "name": "Kal"
            },
            {
                "name": "Jack"
            },
            {
                "name": "Igor"
            }
        ],
        "subjects": [
            "English",
            "Maths"
        ]
    },
    "location": {
        "Dept": [
            "EnglishDept",
            ],
        "BlockNo": 1000
    },
    "statusTracker": {
        "googleFormsURL": "beacon.datazoom.io",
        "totalCount": 3000
    }
}

我尝试过但执行失败的代码是，

struct Class: Decodable {
    let semester: [internalComponents]
    let location: [location]
    let statusTracker: [statusTracker]
    enum CodingKeys: String, CodingKey {
        case semester = "semester1"
        case location = "location"
        case statusTracker = "statusTracker"
    }
}
struct location: Decodable {
    let Dept: [typesSubIn]
    let BlockNo: Int
}
struct statusTracker: Decodable {
    let googleFormsURL: URL
    let totalCount: Int
}


struct internalComponents: Decodable {
    let semester1: [semsIn]
    let subjects: [subjectsIn]
}
struct semsIn: Decodable {
    let nameIn: String
}
struct subjectsIn: Decodable {
    let subjects: String
}
struct Dept: Decodable {
    let Depts: String
}

我知道这是完全错误的，有人能给出实际的格式吗？我实际上对“主题”的格式感到困惑，它也不是作为一个整体来编译的。

Answer 1

有很多问题。

通过部分忽略根对象，您正在犯一个常见的错误。

请看JSON:在顶层有3个键class，location和statusTracker。所有3个键的值都是字典，没有数组。

因为class (小写)是保留字，所以我使用components。顺便说一下，请遵守结构名称以大写字母开头的命名约定。

struct Root : Decodable {
    let components : Class
    let location: Location
    let statusTracker: StatusTracker

    enum CodingKeys: String, CodingKey { case components = "class", location, statusTracker }
}

还有很多其他的问题。这里是其他结构的合并版本

struct Class: Decodable {
    let semester1: [SemsIn]
    let subjects : [String]
}

struct Location: Decodable {
    let dept : [String]
    let blockNo : Int

    enum CodingKeys: String, CodingKey { case dept = "Dept", blockNo = "BlockNo" }
}

struct SemsIn: Decodable {
    let name: String
}

struct StatusTracker: Decodable {
    let googleFormsURL: String // URL is no benefit
    let totalCount: Int
}

现在解码Root

do {
    let result = try decoder.decode(Root.self, from: data)
} catch { print(error) }

Answer 2

看起来你用错误的方式消毒了Class对象。它应该看起来像这样：

struct Class: Decodable {
    let class: [internalComponents]
    let location: [location]
    let statusTracker: [statusTracker]
}

Answer 3

这里有一些事情会导致你的问题。

• 在你的类结构中，你的项被设置为数组，但它们不是数组

• 来调试这些类型的问题，把你的解码包在一个do 块中并打印出错误。它会告诉您无法解析的原因

在我的游乐场上试试这段代码：

let jsonData = """
{
    "class": {
        "semester1": [{
            "name": "Kal"
        }, {
            "name": "Jack"
        }, {
            "name": "Igor"
        }],
        "subjects": [
            "English",
            "Maths"
        ]
    },
    "location": {
        "Dept": [
            "EnglishDept"
        ],
        "BlockNo": 1000
    },
    "statusTracker": {
        "googleFormsURL": "beacon.datazoom.io",
        "totalCount": 3000
    }
}
""".data(using: .utf8)!

struct Response: Decodable {
    let cls: Class
    let location: Location
    let statusTracker: statusTracker

    enum CodingKeys: String, CodingKey {
        case cls = "class"
        case location
        case statusTracker
    }
}

struct Class: Decodable {
    let semester: [SemesterStudents]
    let subjects: [String]

    enum CodingKeys: String, CodingKey {
        case semester = "semester1"
        case subjects
    }
}

struct Location: Decodable {
    let dept: [String]
    let blockNo: Int

    enum CodingKeys: String, CodingKey {
        case dept = "Dept"
        case blockNo = "BlockNo"
    }
}

struct statusTracker: Decodable {
    let googleFormsURL: URL
    let totalCount: Int
}

struct SemesterStudents: Decodable {
    let name: String
}

struct Dept: Decodable {
    let Depts: String
}

do {
    let result = try JSONDecoder().decode(Response.self, from: jsonData)
    print(result)
} catch let error {
    print(error)
}