Sum up from top the bottom of a String Triangle with NON PRIME numbers

Triangle Sum Swift.swift

//Implemented in Swift 4

import Foundation

class ViewController: UIViewController {

    var assignmentString = """
                            215
                          193 124
                         117 237 442
                       218 935 347 235
                     320 804 522 417 345
                   229 601 723 835 133 124
                 248 202 277 433 207 263 257
               359 464 504 528 516 716 871 182
             461 441 426 656 863 560 380 171 923
           381 348 573 533 447 632 387 176 975 449
         223 711 445 645 245 543 931 532 937 541 444
       330 131 333 928 377 733 017 778 839 168 197 197
     131 171 522 137 217 224 291 413 528 520 227 229 928
   223 626 034 683 839 53  627 310 713 999 629 817 410 121
 924 622 911 233 325 139 721 218 253 223 107 233 230 124 233
"""
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Call of the algorithm function with a string defined in triangle format.
        maxSumForTriangle(triangleString: assignmentString)
    }

    /// In this algorithm we first reverse the triangle meaning; starting from the last line of the triangle so that we can
    /// run through all the possible scenarios and find the maximum sum pathway.
    func maxSumForTriangle(triangleString: String) {
        var values = triangleString.components(separatedBy: .newlines).map {
            $0.components(separatedBy: .whitespaces).compactMap(Int.init)
        }
        
        for line in values.indices.reversed() {
                for column in values[line].indices {
                    // Check if the number is prime, if so we make it equal min value of Int
                    if isPrime(values[line][column]) {
                        values[line][column] = Int.min
                        print(values[line][column])
                    } else if line + 1 < values.endIndex {
                        values[line][column] += max(values[line+1][column], values[line+1][column+1])
//                        print(values[line][column])
                    }
                }
            }
        
        print(values[0][0])
    }

    /// Returns a boolean value indicating if a given number is a prime number or not.
    func isPrime(_ number: Int) -> Bool {
        return number > 1 && !(2..<(Int(sqrt(Double(number))) + 1)).contains { number % $0 == 0 }
    }
}