将JSON解析为Struct Swift 4

Question

I am trying to parse some JSON into a struct. Since that seems to be the way I have seen folks do this? The data is a Data object I just got from a URLRequest.

Here is a sample of the JSON:

{
  "policies": [{
    "id": 100,
    "name": "00 Kickoff"
  }, {
    "id": 237,
    "name": "02 Install Program 01"
  }, {
    "id": 13,
    "name": "03 AV Install"
  }, {
    "id": 114,
    "name": "04 - Tag Device"
  }, {
    "id": 102,
    "name": "05 VPN Install"
  }]
}

There are many more items but this is the exact structure of the JSON.

So I wrote a couple of Structs thinking that will hold the data:

struct Policies: Codable {
    let policies: [Policy]

    private enum CodingKeys: String, CodingKey {
        case policies = "policies"
    }
}

struct Policy: Codable {
    let id: String?
    let name: String?

    private enum CodingKeys: String, CodingKey {
        case id = "id"
        case name = "name"
    }
}

Then I try and do the decode:

do {
    let jssPolicies: Policies = try decoder.decode(Policies.self, from: data)
} catch let error as NSError {
    debugPrint("Error: \(error.description)")
    }

But then I get the error:

"Error: Error Domain=NSCocoaErrorDomain Code=4864 \"Expected to decode Array<Any> but found a dictionary instead.\" UserInfo={NSCodingPath=(\n), NSDebugDescription=Expected to decode Array<Any> but found a dictionary instead.}"

I feel like I am close? But who knows perhaps I am not. Any help someone can off on how to take this Data object that I get from the URL request and turn it into JSON would be helpful. I have looked at a few posts but since the structure of the JSON is different I am a bit stuck.

Thanks in Advance, Ed

Answer 1

Actually with the given JSON you should get

Type 'String' mismatch: Expected to decode String but found a number instead.

because the value for key id is an Int . Is this the real JSON?

You get the described error if you try to decode [Policies].self

And you can omit all CodingKeys, if they match the property names you get them for free

struct Policies: Codable {
    let policies: [Policy]
}

struct Policy: Codable {
    let id: Int
    let name: String
}