Want to create particular property value array from array

Question

Having array of employee object, called employees and now I want to create another array called filteremployees which is having only id and date of birth value. Using let filteremployees = employee.map({ $0.id}) I can get array which contains only id value but i want to have id as well dateOfBirth

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
    }
}

are you trying to loop through the one array and add filtered data into another array? — Skywalker
– Skywalker, Commented Sep 26, 2015 at 12:30
@Jatin: One suggestion: Employee is a good candidate for being a struct here. And the properties are good candidates for being declared with let instead of var. Look a what Abizern has done with the FilteredEmployee struct. — Luca Angeletti
– Luca Angeletti, Commented Sep 26, 2015 at 12:50

Luca Angeletti · Accepted Answer · 2015-09-26 12:41:28Z

2

Try this:

let employees : [Employee] = ...
let list: [(Int, NSDate?)] = employees.map { ($0.id, $0.dateOfBirth) }

You must explicitly declare the type of list otherwise you get this error from the compiler

Type of expression is ambiguous without more context.

Tested with Xcode 7 Playground and Swift 2.0.

Hope this helps.

answered Sep 26, 2015 at 12:41

Luca Angeletti

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Abizern · Accepted Answer · 2015-09-26 12:46:29Z

1

You could try using the same map method and returning a tuple of your expected values:

let filter employees: [(Int, NSDate?)] = employee.map({ ($0.id, $0.dateOfBirth) })

Alternatively, and I think this is a better solution, create a new value type and create that with only your required values

struct FilteredEmployee {
    let id: String
    let dateOfBirth: NSDate?

    init(employee: Employee) {
        id = employee.id
        dateOfBirth = employee.dateOfBirth
    }
}

And then you can map the initialiser over the array

    let filteremployees = employee.map { FilteredEmployee($0) }

edited Sep 26, 2015 at 12:46

answered Sep 26, 2015 at 12:38

Abizern

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1 Comment

Luca Angeletti Over a year ago

I was trying the same solution, but your first block of code does not compile.

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