Saved from https://www.codewars.com/kata/5552101f47fc5178b1000050/solutions/swift

my_solution

precedencegroup PowerPrecedence { higherThan: MultiplicationPrecedence }
infix operator ^^ : PowerPrecedence
func ^^ (radix: Int, power: Int) -> Int {
    return Int(pow(Double(radix), Double(power)))
}

func digPow (for number: Int, using power: Int) -> Int {
    
    var num = number
    var pow = power
    var digits:[Int] = []
    var poweredDigits:[Int] = []
    var poweredArraySum:Int
    
    while num > 0 {
        let digit = num % 10
        digits =  [digit] + digits
        num /= 10
        }
    
    for index in digits {
        poweredDigits.append(index ^^ pow)
        pow += 1
    }
    
    
    poweredArraySum = poweredDigits.reduce(0, +)
    
    
    if poweredArraySum % number == 0 {
        return poweredArraySum / number
    } else {
        return -1
    }
  
}

simple solution

import Foundation

func digPow(for number: Int, using power: Int) -> Int {
    let sum = String(number).characters.enumerated().reduce(0) {
        let number = Int(String($1.1))!
        return $0 + Int(pow(Double(number), Double(power + $1.0)))
    }
    
    return sum % number == 0 ? sum / number : -1
}