get distinct elements in an array by object property

Question

I have an array of object. I want to get distinct elements in this array by comparing objects based on its name property

class Item {
var name: String
init(name: String) {
    self.name = name
}
}
let items = [Item(name:"1"), Item(name:"2"), Item(name:"1"), Item(name:"1"),Item(name:"3"), Item(name:"4")]

result:

let items = [Item(name:"1"), Item(name:"2"),Item(name:"3"), Item(name:"4")]

how can I do this in swift?

Answer 1

Here is an Array extension to return the unique list of objects based on a given key:

extension Array {
    func unique<T:Hashable>(by: ((Element) -> (T)))  -> [Element] {
        var set = Set<T>() //the unique list kept in a Set for fast retrieval
        var arrayOrdered = [Element]() //keeping the unique list of elements but ordered
        for value in self {
            if !set.contains(by(value)) {
                set.insert(by(value))
                arrayOrdered.append(value)
            }
        }

        return arrayOrdered
    }
}

For your example you can do:

let uniqueBasedOnName = items.unique{$0.name}