How to parse this type of json format in swift 4 with decodable?

Question

{
  "type": "Success",
  "message": "",
  "fitting": {
    "fitterID": "96ba096c-f0aa-11e7-a67a-76478bc72e4d",
    "fitID": "09d399c0-7d74-4578-a138-5f4b02ba2e80",
    "leftNotesJSON": "[{\"class\":\"FitNote\",\"text\":\"Saddle Down\",\"leftfoot\":false},{\"class\":\"FitNote\",\"text\":\"Saddle Down\",\"leftfoot\":false},{\"class\":\"FootBottomNote\",\"leftfoot\":false}]",
    "rightNotesJSON": "[{\"s3Bucket\":\"8190ba10-d310-11e3-9c1a-0800200c9a66\",\"angle\":0,\"leftfoot\":false,\"shoulderAngle\":0,\"hipAngle\":0,\"s3Key\":\"FD0F5AE6-8193-4980-AD11-C42FEF064B8B\",\"class\":\"AngleNote\",\"kneeAngle\":0}]"
  }
}

please share what you done so far to achieve this? – Abdul Rehman Oct 24 '18 at 06:20 — Abdul Rehman, Oct 24 '18 at 06:20

score 1 · Answer 1 · answered Oct 26 '18 at 19:44

The json in your question is not valid. I'll be using the following json in my answer:

let json = """
{
  "type": "Success",
  "message": "",
  "fitting": {
    "fitterID": "96ba096c-f0aa-11e7-a67a-76478bc72e4d",
    "fitID": "09d399c0-7d74-4578-a138-5f4b02ba2e80",
    "leftNotesJSON": [{"class":"FitNote","text":"Saddle Down","leftfoot":false},{"class":"FitNote","text":"Saddle Down","leftfoot":false},{"class":"FootBottomNote","leftfoot":false}],
    "rightNotesJSON": [{"s3Bucket":"8190ba10-d310-11e3-9c1a-0800200c9a66","angle":0,"leftfoot":false,"shoulderAngle":0,"hipAngle":0,"s3Key":"FD0F5AE6-8193-4980-AD11-C42FEF064B8B","class":"AngleNote","kneeAngle":0}]
  }
}
"""

Let's define decodable structs:

struct Response: Codable {
    let type, message: String
    let fitting: Fitting
}

struct Fitting: Codable {
    let fitterID, fitID: String
    let leftNotesJSON: [LeftNotesJSON]
    let rightNotesJSON: [RightNotesJSON]
}

struct LeftNotesJSON: Codable {
    let leftNotesJSONClass: String
    let text: String?
    let leftfoot: Bool

    //Define the coding keys since the json contains "class" as a key
    enum CodingKeys: String, CodingKey {
        case leftNotesJSONClass = "class"
        case text, leftfoot
    }
}

struct RightNotesJSON: Codable {
    let s3Bucket: String
    let angle: Int
    let leftfoot: Bool
    let shoulderAngle, hipAngle: Int
    let s3Key, rightNotesJSONClass: String
    let kneeAngle: Int

    //Define the coding keys since the json contains "class" as a key  
    enum CodingKeys: String, CodingKey {
        case s3Bucket, angle, leftfoot, shoulderAngle, hipAngle, s3Key
        case rightNotesJSONClass = "class"
        case kneeAngle
    }
}

Let's get the data out of the json:

guard let data = json.data(using: .utf8) else {
    fatalError("Couldn't get data from json")
}

And then decode it

do {
    let response = try JSONDecoder().decode(Response.self, from: data)

    //Here and now you can use the properties of the response
    print(response.type)
    print(response.message)
    print(response.fitting.fitID)
    print(response.fitting.fitterID)
    print(response.fitting.leftNotesJSON.map {$0.leftfoot})
    print(response.fitting.rightNotesJSON.map{$0.kneeAngle})
} catch {
    print(error)
}

score 0 · Answer 2 · answered Oct 24 '18 at 07:42

First, you may have to create models, which confirms to Codable Protocol. You can use any online tools for formatting JSON and creating models. In given code response Model will get parsed data.

   import Foundation
    struct Base : Codable {
        let type : String?
        let message : String?
        let fitting : Fitting?
        enum CodingKeys: String, CodingKey {
            case type = "type"
            case message = "message"
            case fitting = "fitting"
        }
        init(from decoder: Decoder) throws {
            let values = try decoder.container(keyedBy: CodingKeys.self)
            type = try values.decodeIfPresent(String.self, forKey: .type)
            message = try values.decodeIfPresent(String.self, forKey: .message)
            fitting = try values.decodeIfPresent(Fitting.self, forKey: .fitting)
        }
    }


    import Foundation
    struct Fitting : Codable {
        let fitterID : String?
        let fitID : String?
        let leftNotesJSON : String?
        let rightNotesJSON : String?

        enum CodingKeys: String, CodingKey {

            case fitterID = "fitterID"
            case fitID = "fitID"
            case leftNotesJSON = "leftNotesJSON"
            case rightNotesJSON = "rightNotesJSON"
        }

        init(from decoder: Decoder) throws {
            let values = try decoder.container(keyedBy: CodingKeys.self)
            fitterID = try values.decodeIfPresent(String.self, forKey: .fitterID)
            fitID = try values.decodeIfPresent(String.self, forKey: .fitID)
            leftNotesJSON = try values.decodeIfPresent(String.self, forKey: .leftNotesJSON)
            rightNotesJSON = try values.decodeIfPresent(String.self, forKey: .rightNotesJSON)
        }

    }

    let task = URLSession.shared.dataTask(with: <YOUR URL>) { (data, response, error) in
        if let data = data {
            let jsonDecoder = JSONDecoder()
            let responseModel = try jsonDecoder.decode(Base.self, from: data)
        }
    }
    task.resume()

How to parse this type of json format in swift 4 with decodable?

2 Answers2