Simple type safe wrapper around UserDefaults

_Example.swift

extension UserDefaultsKey {
    static var foo: UserDefaultsKey<SomeType> { .init(name: "foo", default: .init(value: "foo")) }
}

struct SomeType: Codable {
    var value: String
}

UserDefaults.standard.get(.foo) // .init(value: "foo")
UserDefaults.standard.set(.foo, .init(value: "bar"))
UserDefaults.standard.get(.foo) // .init(value: "bar")

UserDefaultsKey.swift

struct UserDefaultsKey<T: Codable> {
    var name: String
    var `default`: T
}

extension UserDefaults {
    func get<T>(_ key: UserDefaultsKey<T>) -> T {
        guard
            let data = data(forKey: key.name),
            let box = try? JSONDecoder().decode(Box<T>.self, from: data)
            else { return key.default }

        return box.value
    }

    func set<T>(_ key: UserDefaultsKey<T>, _ value: T?) {
        if let value = value {
            let box = Box(value: value)
            if let data = try? JSONEncoder().encode(box) {
                set(data, forKey: key.name)
            } else {
                removeObject(forKey: key.name)
            }
        } else {
            removeObject(forKey: key.name)
        }
    }
}

private struct Box<T: Codable>: Codable {
    var value: T
}