SetOperations.playground

//: Playground - noun: a place where people can play

import UIKit

func createSetWith(enable: Bool, requestList: [[String : Any]]) -> Set<String> {
    return Set(requestList
        .filter { ($0["enabled"] as? Bool) == enable }
        .map { $0["key"] as? String ?? ""})
}

let sub1 = ["key" : "updates", "enabled": false] as [String : Any]
let sub2 = ["key" : "news", "enabled": true] as [String : Any]
let sub3 = ["key" : "itinerary", "enabled": false] as [String : Any]
let sub4 = ["key" : "cancelations", "enabled": true] as [String : Any]
let requestList = [sub1, sub2, sub3, sub4]

let disabledSubscriptions = ["news", "itinerary"]
let listToEnable = createSetWith(enable: true, requestList: requestList)
let listToDisable = createSetWith(enable: false, requestList: requestList)

let setDisabledSubscriptions = Set(disabledSubscriptions)

let newSet = setDisabledSubscriptions
    .subtracting(listToEnable)
    .union(listToDisable)