How to convert a json payload to a custom object? - json

Question

We have a json payload:
{
"aps": {
"alert": {
"title": "Payload",
"body": "Lets map this thing"
},
},
"type": "alert",
"message": "This is a message",
}
The custom object has been created:
class PushNotificationDetail {
var title: String //operation
var body: String //message
var type: detailType
var message: String?
init(title: String, body: String, type: detailType, message: string?){
self.title = title
self.body = body
self.type = type
self.message = message
}
}
The problem is mapping it correctly to the created object, what would be the best way to achieve this?

Answer 1

You should use Swift4 Codable protocol to initialise your object from the json returned by the api. You will need to restructure your structure to match the data returned by the api:
struct PushNotificationDetail: Codable, CustomStringConvertible {
let aps: Aps
let type: String
let message: String?
var description: String { return aps.description + " - Type: " + type + " - Message: " + (message ?? "") }
}
struct Aps: Codable, CustomStringConvertible {
let alert: Alert
var description: String { return alert.description }
}
struct Alert: Codable, CustomStringConvertible {
let title: String
let body: String
var description: String { return "Tile: " + title + " - " + "Body: " + body }
}
extension Data {
var string: String { return String(data: self, encoding: .utf8) ?? "" }
}
Playground Testing
let json = """
{"aps":{"alert":{"title":"Payload","body":"Lets map this thing"}},"type":"alert","message":"This is a message"}
"""
if let pnd = try? JSONDecoder().decode(PushNotificationDetail.self, from: Data(json.utf8)) {
print(pnd) // "Tile: Payload - Body: Lets map this thing - Type: alert - Message: This is a message\n"
// lets encode it
if let data = try? JSONEncoder().encode(pnd) {
print(data.string) // "{"aps":{"alert":{"title":"Payload","body":"Lets map this thing"}},"type":"alert","message":"This is a message"}\n"
print(data == Data(json.utf8)) // true
}
}

Answer 2

You can do this with a failable initialiser in your PushNotificationDetail class and a chained guard statement:
init?(jsonDict: [String : Any]) {
guard let typeString : String = jsonDict[“type”] as? String,
let message: String = jsonDict[“message”] as? String,
let aps : [String : Any] = jsonDict[“aps”] as? [String : Any],
let alert : [String : String] = aps[“alert”] as? [String : String],
let title : String = alert[“title”],
let body : String = alert[“body”] else { return nil }
// implement some code here to create type from typeString
self.init(title: title, body: body, type: type, message: message)
}
Hope that helps.