Getting Error while decoding the json in swift, failing while decoding

I am trying to decode this json but it keep failing on "failed to decode" line. I validated the json, checked the struct, these looks fine to me. Am i misssing something?

JsonManager.swift

extension Bundle {
    func decode (_ file: String) -> Cities {
        guard let url = self.url(forResource: file, withExtension: nil) else {
            fatalError("Failed to locate \(file) in bundle")
        }
        guard let data = try? Data(contentsOf: url) else {
            fatalError("failed to load \(file) bundle")
        }
        let decoder = JSONDecoder()
        guard let loaded = try? decoder.decode(Cities.self, from: data) else {
             fatalError("Failed to decode \(file) from bundle")
// (Run time error here) Fatal error: Failed to decode cities.json from bundle
        }
        print("loaded")
        return loaded
    }
}

ContentView.swift

var cities = Bundle.main.decode("cities.json")

cities.json

{
  "city": [
    {
      "id": "1",
      "name": "Mumbai",
      "state": "Maharashtra"
    },
    {
      "id": "2",
      "name": "Delhi",
      "state": "Delhi"
    }
]
}

JsonStruct.swift

struct Cities: Codable {
    struct City: Codable {
        let id: String
        let name: String
        let state: String
    }
    let city: [City]
}