Swift 4 decoding json using Codable

user_6222093 0
Viewed 3561

Can someone tell me what I'm doing wrong? I've looked at all the questions on here like from here How to decode a nested JSON struct with Swift Decodable protocol? and I've found one that seems exactly what I need Swift 4 Codable decoding json.

{
"success": true,
"message": "got the locations!",
"data": {
    "LocationList": [
        {
            "LocID": 1,
            "LocName": "Downtown"
        },
        {
            "LocID": 2,
            "LocName": "Uptown"
        },
        {
            "LocID": 3,
            "LocName": "Midtown"
        }
     ]
  }
}

struct Location: Codable {
    var data: [LocationList]
}

struct LocationList: Codable {
    var LocID: Int!
    var LocName: String!
}

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    let url = URL(string: "/getlocationlist")

    let task = URLSession.shared.dataTask(with: url!) { data, response, error in
        guard error == nil else {
            print(error!)
            return
        }
        guard let data = data else {
            print("Data is empty")
            return
        }

        do {
            let locList = try JSONDecoder().decode(Location.self, from: data)
            print(locList)
        } catch let error {
            print(error)
        }
    }

    task.resume()
}

The error I am getting is:

typeMismatch(Swift.Array, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Array but found a dictionary instead.", underlyingError: nil))

codable swift4
3 Answers

After searching lots of thing internet, I certainly figured out this is the sweetest way to print well formatted json from any object.

let jsonString = object.toJSONString(prettyPrint: true)
print(jsonString as AnyObject)
user_66812280

Apple documentation about JSONEncoder ->

struct GroceryProduct: Codable {
    var name: String
    var points: Int
    var description: String?
}

let pear = GroceryProduct(name: "Pear", points: 250, description: "A ripe pear.")

let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted

let data = try encoder.encode(pear)
print(String(data: data, encoding: .utf8)!)

/* Prints:
 {
   "name" : "Pear",
   "points" : 250,
   "description" : "A ripe pear."
 }
*/
user_6063200
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