如何解析一个 JSON 数组数组并通过名称引用内部数组的成员？

Question

在 Swift Playground 中，我尝试解析以下数据：

let jsonMoves:String =

"""
{ "moves":
    [
        [0, 'CAT (7)', 'ACT'],
        [1, 'EXTRA (14)', 'ERXT'],
        [0, 'TOP (22)', 'PO'],
        [1, 'TOY (9)', 'Y']
    ]
 }
"""

为此我创建了 2 个结构：

struct MovesResponse: Codable {
    let moves: [[MoveModel]]
}

struct MoveModel: Codable {
    let mine: Int
    let words: String
    let letters: String
}

并调用：

let decoder = JSONDecoder()

if let movesData = jsonMoves.data(using: .utf8),
   let movesModel = try? decoder.decode(MovesResponse.self, from: movesData),
   movesModel.count > 0 // does not compile
{
    print("Parsed moves: ", movesModel)
} else {
    print("Can not parse moves")
}

不幸的是，上面的代码给我编译错误：

Value of type 'MovesResponse' has no member 'count'

当我删除该行并将 try? 更改为 try! 以查看异常时，我得到错误：

Fatal error: 'try!' expression unexpectedly raised an error: Swift.DecodingError.dataCorrupted(Swift.DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around line 3, column 12." UserInfo={NSDebugDescription=Invalid value around line 3, column 12., NSJSONSerializationErrorIndex=29})))

作为一个 Swift 新手，我认为结构 MoveModel 是错误的。请帮忙

另外我想知道是否可以将内部数组的三个元素称为“mine”、“words”、“letters”？

更新：

我已按照 Joakim 的建议将 jsonMoves 中的单引号更改为双引号（谢谢！），现在的错误是：

Fatal error: 'try!' expression unexpectedly raised an error: Swift.DecodingError.typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "moves", intValue: nil), _JSONKey(stringValue: "Index 0", intValue: 0), _JSONKey(stringValue: "Index 0", intValue: 0)], debugDescription: "Expected to decode Dictionary<String, Any> but found a number instead.", underlyingError: nil))

Answer 1

您可以使用 MoveModel，但由于每个内部数组代表 MoveModel 的一个实例，因此您需要将第一个结构更改为

struct MovesResponse: Codable {
    let moves: [MoveModel]
}

然后您需要 MoveModel 中的自定义 init(from:)，它使用未加密的容器而不是编码键将每个数组解码为 MoveModel 对象。

init(from decoder: Decoder) throws {
    var container = try decoder.unkeyedContainer()
    mine = try container.decode(Int.self)
    words = try container.decode(String.self)
    letters = try container.decode(String.self)
}

与其使用 try? 并打印硬编码消息，我建议您捕获错误并打印它

let decoder = JSONDecoder()
do {
  let movesModel = try decoder.decode(MovesResponse.self, from: data)
    print(movesModel)
} catch {
    print(error)
}

如何解析一个 JSON 数组数组并通过名称引用内部数组的成员？

How to parse a JSON array of arrays and refer to the members of the inner array by names?

json

ios

swift

arrayofarrays

jsondecoder