Trying to figure out how to encode response into swift objects

GistTypes.swift

import Foundation

struct Gist:Codable {
    let url: String
    let files: [File]
}

struct File:Codable {
    let filename,type,language,rawURL: String
    let size: Int

    enum CodingKeys: String, CodingKey {
        case filename,type,language
        case rawURL = "raw_url"
        case size
    }
}

response.json

[{
    "url": "https://api.github.com/gists/8ee96d320c7b967bb479d00c3db6c450",
    ...
    "files": {
        "fileName1.js": {
            "filename": "fileName1.js",
            "type": "application/javascript",
            "language": "JavaScript",
            "raw_url": "https://gist.githubusercontent.com/KevinGutowski/8ee96d320c7b967bb479d00c3db6c450/raw/ad218219601e0791f1baa2f59bd2d4b4189cdd25/fileName1.js",
            "size": 26
        },
        "fileName2.js": {
            "filename": "fileName2.js",
            "type": "application/javascript",
            "language": "JavaScript",
            "raw_url": "https://gist.githubusercontent.com/KevinGutowski/8ee96d320c7b967bb479d00c3db6c450/raw/64aa0a82a063a391a53b07f848411d8d8df407d4/fileName2.js",
            "size": 19
        }
    }
}, ...]