Where is the class definition located if it is used as a field inside a structure?

When a class is used as a field inside a structure in Swift, the class definition is usually located in the same file or module where the structure is declared, or it is imported from another module. It is important that the class is accessible within the scope of the structure so that the compiler can recognize the field's type. For example:

class Person {
    var name: String
    init(name: String) {
        self.name = name
    }
}

struct Employee {
    var person: Person
    var position: String
}

Here, the Person class is defined above the Employee structure in the same file.