PrimesFromArray.swift

//Select prime number from array.

let primeNumbers = numbers.filter{
    (number) in
    for var i = 2; i <= number/2; i++ {
        if number%i == 0 { return false }
    }
    return true
} 

//OR 

func numberIsPrime(number : Int) -> Bool {
    for var i = 2; i <= number/2; i++ {
        if number%i == 0 { return false }
    }
    return true
}

//Declaration
let numbers = [1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12 ,13, 15, 17, 19, 23]

//Way 1
primeNumbers //Output -> [1, 2, 3, 5, 7, 11, 13, 17, 19, 23]

//Way 2
let primeNumbers2 = numbers.filter { numberIsPrime($0) } 
primeNumbers2 //Output -> [1, 2, 3, 5, 7, 11, 13, 17, 19, 23]