ios - 错误: value of type 'Optional<NSMutableArray>' has no subscripts Array[0] in Swift iOS

Question

我正在从 Objective C 类中获取一些数据。这是我的“dataArray”数据:

Optional(<__NSArrayM 0x2818cff60>(
{
    date = 1574164423;
    shakeState = 1;
},
{
    date = 1574164431;
    shakeState = 1;
}
)
)

我创建了一个模态类“ShakeInfo”，其中包含日期和 shakeState 值。

我只想将此数组转换为“ShakeInfo”对象数组。我的问题是当我尝试打印“dataArray[0]”时出现错误:

error: <EXPR>:3:1: error: value of type 'Optional<NSMutableArray>' has no subscripts
dataArray[0]

如何按索引读取该数组值。请多多指教。

编辑:

这是我获取 dataArray 后的代码:

do {
     let data = try JSONSerialization.data(withJSONObject: dataArray!)
     let responseStr = String(data: data, encoding: .utf8)!

     print(responseStr)//[{"date":"1574164424","shakeState":1},{"date":"1574164430","shakeState":1}]

     var shakeInfoDetails = [ShakeInfo]()

     //how to add 'responseStr' value in the shakeInfoDetails Modal Array

     } catch {

      print("JSON serialization failed: ", error)
     }

Answer 1

let data = #"[{"date":"1574164424","shakeState":1},{"date":"1574164430","shakeState":1}]"#.data(using: .utf8)!

//Model

struct ModelRecord : Codable {

    var date : String
    var shakeState : Int
}

class Model {

    var date : Date
    var shakeState : Int

    init?(record: ModelRecord) {

        guard let secondsFrom1970 = Double(record.date) else {
            return nil
        }

        date = Date(timeIntervalSince1970: secondsFrom1970)
        shakeState = record.shakeState
    }
}

//Decoding

let decoder = JSONDecoder()

do {
    let records = try decoder.decode([ModelRecord].self, from: data)

    let models = records.compactMap { Model(record: $0) }

}
catch {
    print("Decoding Error: \(error)")
}

原始问题的答案:

let a1 : NSMutableArray? = NSMutableArray(array: ["A", "B", "C"])

a1?.object(at: 2)

请阅读以下内容:

• Swift 中的选项
• 可编码 - https://developer.apple.com/documentation/foundation/archives_and_serialization/encoding_and_decoding_custom_types
• Swift 标准库中的数组
• Foundation 中定义的 NSMutableArray