SWIFT中正则表达式验证邮箱

在playground内写入以下代码，正则关键字跟其它语言的没什么区别

class Regex {
    let internalExpression:NSRegularExpression
    let pattern:String

    init(pattern:String) {
        self.pattern = pattern
        var error:NSError?
        self.internalExpression = NSRegularExpression(pattern: pattern, options: NSRegularExpressionOptions.CaseInsensitive, error: &error)!
    }

    func match(input:String) -> Bool {
        let matches = self.internalExpression.matchesInString(input, options: nil, range: NSMakeRange(0, count(input)))
        return matches.count > 0
    }
}

var email_regex = case Email = "^([a-zA-Z0-9]+([._\\-])*[a-zA-Z0-9]*)+@([a-zA-Z0-9])+(.([a-zA-Z])+)+$"

var regex = Regex(pattern:email_regex)

regex.match("service@t.com")  //RETURN true
regex.match("ken.ngai@tao.com.cn") //RETURN true
regex.match("buddy_wei@frend.org") //RETURN true

CaseInsensitive：大小写不敏感