Storing weather forecast data in Swift - swift

Question

I want to make an application which requires a lot of weather forecast data, three cities, seven days, 24 hours and six values in every hour of forecast.
I'm using the Dark Sky API and pod called ForecastIO.
What should I use for storage? CoreData or Realm? I was told that Realm is a lot of easier to work with and it's also more efficient. I looked into code and for a beginner it is much easier and not dealing with any graphs is also plus, but if it needs to be done, I'll study it. And how should I structure it?
I tried this but Realm accepts only basic data types, so it won't work.
HourlyWeather.swift
import Foundation
import RealmSwift
class HourlyWeather: Object {
#objc dynamic var temperature: Double = 0
#objc dynamic var wind: Double = 0
#objc dynamic var precip: Double = 0
#objc dynamic var humidity: Double = 0
#objc dynamic var uvIndex: Int = 0
#objc dynamic var icon: String = ""
}
DailyWeather.swift
import Foundation
import RealmSwift
class DailyWeather: Object {
#objc dynamic var day = [HourlyWeather()] // I understand that this is a no-no for Realm
}
CityWeather.swift
import Foundation
import RealmSwift
class CityWeather: Object {
#objc dynamic var city = [DailyWeather()] // The same
}
I wanted this code to be accessible as
City.day[index].hour[index].temperature
for example

Answer 1

You need to use List instead of Array when you want to store a collection of Realm objects as a property of another object. For more information, read the Many-to-many relationships part of the official docs (but I'd suggest going through the whole documentation, since it gives a really good starting point for using Realm).
class DailyWeather: Object {
let day = List<HourlyWeather>()
}
class CityWeather: Object {
let city = List<DailyWeather>()
}

Answer 2

You need to declare a property of type List. See the Many to Many docs
class DailyWeather: Object {
let city = List<DailyWeather>()
}