解码嵌套对象swift4 Codable

Question

API 发给我这个 json :

{
"name": "John Doe",
"details": [{
    "name": "exampleString"
}, {
    "name": [1, 2, 3]
}]

}

这里的问题是细节数组有两个不同值类型的字典。如何使用 swift4 的可解码协议在模型中解码这个 json ？

Answer 1

我不建议您使用异构类型构建 JSOn；在这种情况下 details.name 可以是字符串或 Int 数组。虽然你可以做到这一点 Swift，但它有点混乱，因为它默认是一种静态类型的语言。如果您无法将 JSON 更改为更清洁的东西，这里展示了您如何选择使用 Any 的动态行为。

//: Playground - noun: a place where people can play
import PlaygroundSupport
import UIKit

let json = """
{
"name": "John Doe",
"details": [{
"name": "exampleString"
}, {
"name": [1, 2, 3]
}]
}
"""


struct Detail {
    var name: Any?
    var nameString: String? {
        return name as? String
    }
    var nameIntArray: [Int]? {
        return name as? [Int]
    }
    enum CodingKeys: CodingKey {
        case name
    }
}

extension Detail: Encodable {
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        if let string = name as? String {
            try container.encode(string, forKey: .name)
        }
        if let array = name as? [Int] {
            try container.encode(array, forKey: .name)
        }
    }
}


extension Detail: Decodable {
    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        if let string = try? values.decode(String.self, forKey: .name) {
            name = string
        } else if let array = try? values.decode(Array<Int>.self, forKey: .name) {
            name = array
        }
    }
}

struct Record: Codable {
    var name: String
    var details: [Detail]
}

let jsonDecoder = JSONDecoder()
let record = try! jsonDecoder.decode(Record.self, from: json.data(using: .utf8)!)
print("\(record.details.first!.name!) is of type: \(type(of:record.details.first!.name!))")
print("\(record.details.last!.name!) is of type: \(type(of:record.details.last!.name!))")

输出是：

exampleString is of type: String
[1, 2, 3] is of type: Array<Int>

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