This is how you would do it in Swift, as per StackOverflow:

func isValidEmail(_ email: String) -> Bool {
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"

    let emailPred = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
    return emailPred.evaluate(with: email)
}

However, the

NSPredicate

constructor has different signature when used in

iosMain

. Is this even a constructor in Swift?

A Objective-C code from StackOverflow works better:

- (BOOL)validateEmailWithString:(NSString*)email
{
    NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"; 
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex]; 
    return [emailTest evaluateWithObject:email];
}

but somehow won't compile when I rewrite this in Kotlin:

fun emailValidation(email:String): Boolean {
    val emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,6}"
    val predicate = NSPredicate.predicateWithFormat("SELF MATCHES %@", emailRegex)
    return predicate.evaluateWithObject(email)
}

It fails with this error:

Passing String as variadic Objective-C argument is ambiguous; cast it to NSString or pass with '.cstr' as C string

I don't want to use any 3rd party libraries for this. I'm learning KMM and want to do this on my own, especially because nobody should really use 3rd parties for such a simple task as email validation essentially is, but not in KMM?

And from your experience, how much proficiency is needed in Swift or even Obj-C to get the most out of KMM? I'm coming from a Android/Java/Kotlin background