Extracting Email Domain in MyPlayground - xcode

Question

I'm developing a chat application. Users will be required to sign up using a university email address.
My app will heavily rely on compartmentalizing users using a UnivID (University ID) which will be the '#' symbol along with the email domain. For example, if a user signs up using any of the following email addresses : jsmith#mail.havard.edu, jsmith#havard.edu, or jsmith#student.havard.edu. The UnivID = '#havard.edu'
I'm new to coding so I hope not to insult your intelligence if this is easy to implement.
Cheers

Answer 1

Here is an algorithm I created to parse the domain and extension from an email address. I used a hardcoded list of the most common domain suffixes to help ensure I don't return just the suffix part of the email if it has a 2 part domain suffix, like "co.uk" or "ca.gov".
You would just need to prepend "#" onto the resulting domain for your use case.
class func parseDomain(fromEmail email: String) -> String? {
let suffixList = ["com", "edu", "gov", "int", "mil", "net", "org", "xyz", "biz", "info", "ai", "io", "co", "ly", "eu", "cn", "ru", "nl", "de", "uk"]
guard let emailDomains = email.components(separatedBy: "#").last else {
return nil
}
let domainParts = emailDomains.components(separatedBy: ".")
guard domainParts.count >= 2 else {
return nil
}
var domain = domainParts[domainParts.count - 2] + "." + domainParts[domainParts.count - 1]
let secondLastComponent = domainParts[domainParts.count - 2]
if suffixList.contains(secondLastComponent) && domainParts.count >= 3 {
// we want to avoid returning things like co.uk, or com.au,
// so if the 2nd last component is a common suffix, return the last 3 parts instead.
domain = domainParts[domainParts.count - 3] + "." + domainParts[domainParts.count - 2] + "." + domainParts[domainParts.count - 1]
}
return domain
}

Answer 2

Latest 2020, Swift 5.2, XCode 11.4.1
Code that works for all inputs
let example = "email_id#gmail.com"
let components = example.components(separatedBy: "#")
if components.count > 1 {
let domain = components[1]
// domain has value gmail.com
}

Answer 3

I assume that you actually want everything after the ampersand. If that is the case then this code will work.
let example = "jsmith#student.harvard.edu"
let univId = "#" + example.componentsSeparatedByString("#")[1]
// "#student.harvard.edu"
If you really only want the last two parts of an extended domain string then this will work.
let example = "jsmith#student.harvard.edu"
let domain = example.componentsSeparatedByString("#")
let parts = domain.componentsSeparatedByString(".")
let univId = "#" + parts[parts.count - 2] + "." + parts[parts.count - 1]
// #harvard.edu