Swift - How to get indexes of filtered items of array

Question

let items: [String] = [\"A\", \"B\", \"A\", \"C\", \"A\", \"D\"]

items.whatFunction(\"A\") // -> [0, 2, 4]
items.whatFunction(\"B\") // -> [1]

Answer 1

just copy and paste

extension Array {
  func whatFunction(_ ids :  String) -> [Int] {

    var mutableArr = [Int]()
    for i in 0..<self.count {
        if ((self[i] as! String) == ids) {
            mutableArr.append(i)
        }
    }
        return mutableArr 
  }

}

Answer 2

/*
let p_last = [51,42]
let inds1 = [1,3,51,42,4]
let idx1 = Array(inds1.filter{ p_last.contains($0) }.indices)
 */

How can we do this to return index [2, 3], that is, elements 51 and 42 in inds1.

Answer 3

you can use it like that :

 let items: [String] = ["A", "B", "A", "C", "A", "D"]

        let indexes = items.enumerated().filter {
            $0.element == "A"
            }.map{$0.offset}

        print(indexes)