#19: Validate Email Addresses in Swift

There is no perfect email regex. The real validation step is whether the address can actually receive mail, so the safest approach is a simple client-side syntax check followed by server-side verification.

A pragmatic local check can look like this:

func isValidEmail(_ value: String) -> Bool {
    let pattern = #"^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}$"#
    return value.range(of: pattern, options: [.regularExpression, .caseInsensitive]) != nil
}

isValidEmail("me@example.com") // true
isValidEmail("not-an-email")   // false

This accepts the most common real-world addresses without trying to implement the full RFC grammar in your app.

Treat this as an early user-feedback step only. Disposable domains, typos, and unreachable mailboxes still need to be caught on the backend or by an email confirmation flow.