如何在Swift中限制用户名的字符

func validateUsername(username: String) -> Bool {
    let pattern = "^[a-zA-Z0-9_-]{4,16}$" // 只允许字母、数字、下划线和减号，长度在4到16个字符之间
    let regex = try! NSRegularExpression(pattern: pattern, options: [])
    let range = NSRange(location: 0, length: username.utf16.count)
    let matches = regex.matches(in: username, options: [], range: range)
    return !matches.isEmpty
}

let username = "myUsername"
if validateUsername(username: username) {
    print("用户名合法")
} else {
    print("用户名不合法")
}