Unique values of Array of items

UniqueValuesOfArray.swift

import Foundation

let test = [1,2,3,4,1,2,2,5,20,2,1,7]

// 1- if order of items is important:
extension Sequence where Element: Hashable {
    func unique() -> [Element] {
        var seen: Set<Element> = []
        return filter { seen.insert($0).inserted }
    }
}

test.unique()


// 3- or using NSOrderedSet

Array(NSOrderedSet(array: test))


// 2- if order of items is not important, you can simply use

Array(Set(test))