To reinforce what we learned in this chapter, let's look at one more example. For this example, we will create a function that will test to see if a string value contains a valid IPv4 address or not. An IPv4 address is the address assigned to a computer that uses the Internet Protocol to communicate. An IP address consists of four numeric values, ranging from 0-255, separated by a dot (period). An example of a valid IP address is 10.0.1.250:
func isValidIP(ipAddr: String?) -> Bool {
guard let ipAddr = ipAddr else {
return false
}
let octets = ipAddr.characters.split { $0 == "."}.map{String($0)}
guard octets.count == 4 else {
return false
}
func validOctet(octet: String) -> Bool {
guard let num = Int(String(octet))
where num >= 0 && num < 256 else {
return false
}
return true
}
for octet in octets {
guard validOctet(octet) else...