ios - Get an array of property values from an object array

Question

There's a class called Employee.

class Employee {

    var id: Int
    var firstName: String
    var lastName: String
    var dateOfBirth: NSDate?

    init(id: Int, firstName: String, lastName: String) {
        self.id = id
        self.firstName = firstName
        self.lastName = lastName
    }
}

And I have an array of Employee objects. What I now need is to extract the ids of all those objects in that array into a new array.

I also found this similar question. But it's in Objective-C so it's using valueForKeyPath to accomplish this.

How can I do this in Swift?

Answer 1

You can use the map method, which transform an array of a certain type to an array of another type - in your case, from array of Employee to array of Int:

var array = [Employee]()
array.append(Employee(id: 4, firstName: "", lastName: ""))
array.append(Employee(id: 2, firstName: "", lastName: ""))

let ids = array.map { $0.id }