Combine two arrays by id - arrays

Question

I have two arrays and I need to combine them by an id. This is how it looks like:
Every single Station has its own sensors. One, two, three or even none. We can find them thanks to ids. Station has an id property, and Sensors are owners of stationId properties. Unfortunately I can't to download them together in one array, so I have to use two arrays. I want to display them in the list view, so I have to create array of objects where the data of both lists form one list. I have created combined array, but there every Stations has only one Sensor and this my problem.
I can't make array where Stations are owners more than one Sensor. In the code below you can see, that there is a problem with accessing elements. It always takes the first index, but I don't know how to get another ones with same id. I'm stuck
Station:
[{
"id": 14,
"stationName": "Działoszyn",
"gegrLat": "50.972167",
"gegrLon": "14.941319",
"city": {
"id": 192,
"name": "Działoszyn",
"commune": {
"communeName": "Bogatynia",
"districtName": "zgorzelecki",
"provinceName": "DOLNOŚLĄSKIE"
}
},
"addressStreet": null
}]
Sensors:
[{
"id": 92,
"stationId": 14,
"param": {
"paramName": "pył zawieszony PM10",
"paramFormula": "PM10",
"paramCode": "PM10",
"idParam": 3
}
},
{
"id": 88,
"stationId": 14,
"param": {
"paramName": "dwutlenek azotu",
"paramFormula": "NO2",
"paramCode": "NO2",
"idParam": 6
}
}]
Edited code:
func setAddItemList(stations: [Station], sensors: [Sensor]) {
var stationItems = [StationItem]()
var sensorItems = [SensorItem]()
sensors.forEach { sensor in
guard let index = stations.firstIndex(where: { $0.id == sensor.stationId}) else {
print("Failed to find a station for sensor \(sensor.id)")
return
}
let sensorItem = SensorItem(
id: sensor.id,
stationId: sensor.stationId,
param: ParamItem(
paramName: sensor.param?.paramName ?? "",
paramFormula: sensor.param?.paramFormula ?? "",
paramCode: sensor.param?.paramCode ?? "",
idParam: sensor.param?.idParam ?? 0))
sensorItems.append(sensorItem)
if sensorItems.count == sensors.count {
let stationItem = stations.map { station in
StationItem(
id: station.id,
stationId: sensor.stationId,
cityName: station.city?.name ?? "",
addressStreet: station.addressStreet!,
sensor: stationItems[index].sensors?.append(sensorItem) ?? []
)
}
stationItems.append(contentsOf: stationItems)
}
}
I also tested Dictionaries, but I had the same problem.

Answer 1

First map Station to StationItem
var stationItems = stations.map { station in
StationItem(
id: station.id,
stationId: sensor.stationId,
cityName: station.city?.name ?? "",
addressStreet: station.addressStreet!,
sensor: [])
}
Then apply my solution from your previous question but instead of appending a Sensor object you first map it to a SensorItem object as you are doing in your code above