Prime numbers print from range 2...100

I have been assigned with a task to print prime numbers from a range 2...100. I've managed to get most of the prime numbers but can't figure out how to get rid of 9 and 15, basically multiples of 3 and 5. Please give me your suggestion on how can I fix this.

for n in 2...20 {
    if n % 2 == 0 && n < 3{
        print(n)
    } else if n % 2 == 1 {
        print(n)
    } else if n % 3 == 0 && n > 6  {
    }
}

This what it prints so far:

2
3
5
7
9
11
13
15
17
19

One of effective algorithms to find prime numbers is Sieve of Eratosthenes. It is based on idea that you have sorted array of all numbers in given range and you go from the beginning and you remove all numbers after current number divisible by this number which is prime number. You repeat this until you check last element in the array.

There is my algorithm which should do what I described above:

func primes(upTo rangeEndNumber: Int) -> [Int] {
    let firstPrime = 2
    guard rangeEndNumber >= firstPrime else {
        fatalError("End of range has to be greater than or equal to \(firstPrime)!")
    }
    var numbers = Array(firstPrime...rangeEndNumber)

    // Index of current prime in numbers array, at the beginning it is 0 so number is 2
    var currentPrimeIndex = 0

    // Check if there is any number left which could be prime
    while currentPrimeIndex < numbers.count {
        // Number at currentPrimeIndex is next prime
        let currentPrime = numbers[currentPrimeIndex]

        // Create array with numbers after current prime and remove all that are divisible by this prime
        var numbersAfterPrime = numbers.suffix(from: currentPrimeIndex + 1)
        numbersAfterPrime.removeAll(where: { $0 % currentPrime == 0 })

        // Set numbers as current numbers up to current prime + numbers after prime without numbers divisible by current prime
        numbers = numbers.prefix(currentPrimeIndex + 1) + Array(numbersAfterPrime)

        // Increase index for current prime
        currentPrimeIndex += 1
    }

    return numbers
}

print(primes(upTo: 100)) // [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
print(primes(upTo: 2)) // [2]
print(primes(upTo: 1)) // Fatal error: End of range has to be greater than or equal to 2!