Parsing JSON with multiple identical identifiers in Swift - json

Question

Im trying to parse JSON data from an RestAPI that gives me energy data for Norway (https://driftsdata.statnett.no/restapi/ProductionConsumption/GetLatestDetailedOverview)
<ProductionConsumptionOverviewViewModel xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/Statnett.Driftsdata.RestApi.Models">
<ConsumptionData>
...
</ConsumptionData>
<Headers>
...
</Headers>
<HydroData>
<ProdConsOverViewModelItem>
<style>hydro</style>
<textTranslationId>General.Hydro</textTranslationId>
<titleTranslationId i:nil="true"/>
<value/>
</ProdConsOverViewModelItem>
<ProdConsOverViewModelItem>
<style i:nil="true"/>
<textTranslationId i:nil="true"/>
<titleTranslationId>ProductionConsumption.HydroSEDesc</titleTranslationId>
<value>4 840</value>
I know it reads like XML but the documentation said JSON so here goes. Im having the same issues reading it as XML still so.
I manage to read the JSON response fine, but Im having trouble "digging down" to the correct spot since the identifiers are the same for the different regions. Let say I wanted the data for the Hydro production below (see screenshot). How would i get that? Ive tries setting the [titleTranslationId] == "ProductionConsumption.HydroSEDesc" but that didnt work.
It looks like XML but the documentation said JSON ? which is why im trying to treat it as JSON.
<ProductionConsumptionOverviewViewModel xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/Statnett.Driftsdata.RestApi.Models">
<ConsumptionData>
...
</ConsumptionData>
<Headers>
...
</Headers>
<HydroData>
<ProdConsOverViewModelItem>
<style>hydro</style>
<textTranslationId>General.Hydro</textTranslationId>
<titleTranslationId i:nil="true"/>
<value/>
</ProdConsOverViewModelItem>
<ProdConsOverViewModelItem>
<style i:nil="true"/>
<textTranslationId i:nil="true"/>
<titleTranslationId>ProductionConsumption.HydroSEDesc</titleTranslationId>
<value>4 840</value>
API response Screenshot
Im using SwiftyJSON to handle the response.
I found some other treads but couldnt get it to work for me. Anyone able to help? Heres my code:
func getEnergyData(url: String){
AF.request(url, method: .get).responseJSON{ response in
switch response.result {
case .success(let json):
print("json success")
//print(json)
let energyJSON : JSON = JSON(response.result)
self.updateEnergyData(json: energyJSON)
case .failure(let error):
print(error)
}
}
}
trying to parse it:
func updateEnergyData(json : JSON){
if let results = json["ProductionConsumptionOverviewViewModel"]["HydroData"]["ProdConsOverViewModelItem"]["value"].double{
print(results)
}
else{
print("parse fail")
}
}
}

Answer 1

When accessing this endpoint via a browser, the API returns XML, but otherwise it returns JSON.
No need for SwiftyJSON or other libraries, instead use Swift's Codable protocol.
For example, make a struct representing the object to decode:
struct HydroData: Decodable {
let value: String
let textTranslationId: String?
let titleTranslationId: String?
let style: String?
}
And another one to get these objects from their array:
struct HydroResult: Decodable {
let HydroData: [HydroData]
}
Then once you have downloaded the data from the endpoint, decode it, and use filter to find, in the array, the object you need:
let url = URL(string: "https://driftsdata.statnett.no/restapi/ProductionConsumption/GetLatestDetailedOverview")!
let task = URLSession.shared.dataTask(with: url) { data, response, error in
guard let data = data else {
print("No data")
return
}
do {
let result = try JSONDecoder().decode(HydroResult.self, from: data)
if let seDesc = result.HydroData.filter({ $0.titleTranslationId == "ProductionConsumption.HydroSEDesc" }).first {
print(seDesc.value)
} else {
print("Error: no value")
}
} catch {
print(error.localizedDescription)
}
}
task.resume()
Note that the return type for value is a String, and in it the numbers are already formatted, and because of that you cannot directly convert them to Int or Double, you would have to use a custom formatter, but this is an entirely different topic.