Check empty string in Swift?

A concise way to check if the string is nil or empty would be:

var myString: String? = nil

if (myString ?? "").isEmpty {
    print("String is nil or empty")
}

There is now the built in ability to detect empty string with .isEmpty:

if emptyString.isEmpty {
    print("Nothing to see here")
}

Apple Pre-release documentation: "Strings and Characters".