Append unique values to an array in swift - arrays

Question

I haven't found anything on that in Swift. Have found how to find unique values on an array, but not this. Sorry if it sounds quite basic...
But I have the following array
var selectedValues = [String]()
And the following value that comes from a Parse query
var objectToAppend = object.objectForKey("description")! as! String
this is how I'am doing it at the moment.
self.selectedHobbies.append(objectToAppend)
But because the query happens repeated times, it ends up appending repeated values. It works, but I just want to not waste memory and only keep unique values.
Any ideas on how to solve that in swift?

Answer 1

You can use a Set which guarantees unique values.
var selectedValues = Set<String>()
// ...
selectedValues.insert(newString) // will do nothing if value exists
Of course, the elements of a Set are not ordered.
If you want to keep the order, just continue with the Array but check before you insert.
if !selectedValues.contains("Bar") { selectedValues.append("Bar") }

Answer 2

I guess that your problem was resolved but I add my answer for next developers who's facing same problem :)
My solution is to write an extension of Array to add elements from an array with a distinct way:
here the code :
extension Array{
public mutating func appendDistinct<S>(contentsOf newElements: S, where condition:#escaping (Element, Element) -> Bool) where S : Sequence, Element == S.Element {
newElements.forEach { (item) in
if !(self.contains(where: { (selfItem) -> Bool in
return !condition(selfItem, item)
})) {
self.append(item)
}
}
}
}
example:
var accounts: [Account]
let arrayToAppend: [Account]
accounts.appendDistinct(contentsOf: arrayToAppend, where: { (account1, account2) -> Bool in
return account1.number != account2.number
})