Here's a stupid code paring test

letter-occurance-swift

// Write a function that outputs the letters that repeats in "Hello World"

import Foundation

func letterOccuranceCount(word1: String) -> Bool {
    
    let letters = word1.map { String($0) }

    // get  duplicates
    let duplicates = Array(Set(letters.filter({ (i: String) in letters.filter({ $0 == i }).count > 1})))
  
    // remove duplicates from str
    for item in duplicates {
        if duplicates.count > 1 {
            print(duplicates, item)
        }
    }
    return true
}

letterOccuranceCount(word1: "Hello world!")