How to find and display repeated elements within an Array in Swift 4

There are two ways to understand this question, whether you want to know how much a given element repeats in an array, or how often each element repeats itself.

Let's say you have an array of Strings:

 var names = ["George", "Fabio", "Maria", "Fabio", "Eugenia", "Maria", "Maria"]

If you want to know the amount of repetitions that each element has inside that array you can go through this array and store within a dictionary each repetition where the key is the item and the value is the amount that this item repeated as:

//Dicionário para guardar quantas vezes cada nome foi repetido 
var counts: [String: Int] = [:]

//Percorre todos elementos no array
for name in names {
   //Ele adiciona mais 1 ao contador do nome se estiver repetido
   counts[name] = (counts[name] ?? 0) + 1
}
//Imprime o resultado de todas repetições 
print(counts)

The result is

["Maria": 3, "George": 1, "Eugenia": 1, "Fabio": 2]

If you just want to know how many times an element is repeated in the array, you only need one for and compare:

var nameToCount = "Maria"
var result = 0

for name in names{
   if name == nameToCount{
      result = result + 1
   }
}
print("O nome:",nameToCount,"Repetiu",result, "x")

Result:

O nome: Maria Repetiu 3 x