KeyPath_People.swift

struct Address {
    let street: String
    let city: String
    let id: String?
}

struct Person {
    let name: String
    let address: Address
}

let people = [
    Person(name: "Tom",address: Address(street: "Regent Street", city: "London", id: nil)),
    Person(name: "Dick", address: Address(street: "", city: "Nottingham", id: nil)),
    Person(name: "Harry", address: Address(street: "", city: "London", id: "1b0d")),
    Person(name: "Alice", address: Address(street: "London Road", city: "Edinburgh", id: nil)),
    Person(name: "Bob", address: Address(street: "The Avenue", city: "Nottingham", id: "0xg2")),
    Person(name: "Charles", address: Address(street: "", city: "Leicester", id: nil)),
]