NationalIdValidate.swift

func validate(id: String) -> Bool {
    guard id.characters.count < 11, let num = Int64(id) else { return false }
    guard (num / 10) % 1000000 > 0 else { return false }
    let checkNumber = Int(num % 10)
    let digits = id.characters.map { Int(String($0))! }
    let digitCount = digits.count
    let sum = digits.dropLast().enumerated().reduce(0) { $0 + (digitCount - $1.offset) * $1.element }
    let r = sum % 11
    return (r < 2 && checkNumber == r) || (r >= 2 && checkNumber == (11 - r))
}