public extension Int {
/// returns number of digits in Int number
public var digitCount: Int { get { return numberOfDigits(in: self) }
}
/// returns number of useful digits in Int number
public var usefulDigitCount: Int { get { var count = 0 for digitOrder in 0..<self.digitCount { /// get each order digit from self let digit = self % (Int(truncating: pow(10, digitOrder + 1) as NSDecimalNumber)) / Int(truncating: pow(10, digitOrder) as NSDecimalNumber) if isUseful(digit) { count += 1 } } return count }
}
// private recursive method for counting digits
private func numberOfDigits(in number: Int) -> Int { if number < 10 && number >= 0 || number > -10 && number < 0 { return 1 } else { return 1 + numberOfDigits(in: number/10) }
}
// returns true if digit is useful in respect to self
private func isUseful(_ digit: Int) -> Bool { return (digit != 0) && (self % digit == 0)
}