我更喜欢用扩展名。此外，这个url http://emailregex.com可以帮助您测试regex是否正确。事实上，该站点为某些编程语言提供了不同的实现。我分享了Swift 3的实现。

extension String {
    func validateEmail() -> Bool {
        let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,6}"
        return NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluate(with: self)
    }
}

//Email validation
func validateEmail(enterEmail:String) -> Bool{
    let emailFormat = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"
    let emailPredicate = NSPredicate(format:"SELF MATCHES %@",emailFormat)
    return emailPredicate.evaluate(with:enterEmail)
}

100%工作和测试

我建议使用它作为String的扩展:

extension String {    
    public var isEmail: Bool {
        let dataDetector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue)

        let firstMatch = dataDetector?.firstMatch(in: self, options: NSRegularExpression.MatchingOptions.reportCompletion, range: NSRange(location: 0, length: length))

        return (firstMatch?.range.location != NSNotFound && firstMatch?.url?.scheme == "mailto")
    }

    public var length: Int {
        return self.characters.count
    }
}

要使用它:

if "hodor@gameofthrones.com".isEmail { // true
    print("Hold the Door")
}

对于那些还在寻找答案的人，请看看下面的框架;

ATGvalidator

它是一个基于规则的验证框架，可以处理大部分开箱即用的验证。最重要的是，它有表单验证器，支持同时验证多个文本字段。

要验证电子邮件字符串，请使用以下方法;

"abcd.hhs@some.com".satisfyAll(rules: [StringRegexRule.email]).status

如果你想验证从文本字段的电子邮件，尝试下面的代码;

textfield.validationRules = [StringRegexRule.email]
textfield.validationHandler = { result in
    // This block will be executed with relevant result whenever validation is done.
    print(result.status, result.errors)
}
// Below line is to manually trigger validation.
textfield.validateTextField()

如果您想在文本框中输入或当焦点更改到另一个字段时验证它，请添加以下行之一;

textfield.validateOnInputChange(true)
// or
textfield.validateOnFocusLoss(true)

请在链接处查看自述文件以获取更多用例。

我改进了@Azik的答案。我允许使用准则允许的更多特殊字符，并返回一些无效的额外边缘情况。

小组认为这里只允许本地部分的。_%+-是不正确的。参见@Anton Gogolev对这个问题的回答或参见下文:

The local-part of the email address may use any of these ASCII characters: uppercase and lowercase Latin letters A to Z and a to z; digits 0 to 9; special characters !#$%&'*+-/=?^_`{|}~; dot ., provided that it is not the first or last character unless quoted, and provided also that it does not appear consecutively unless quoted (e.g. John..Doe@example.com is not allowed but "John..Doe"@example.com is allowed); space and "(),:;<>@[\] characters are allowed with restrictions (they are only allowed inside a quoted string, as described in the paragraph below, and in addition, a backslash or double-quote must be preceded by a backslash); comments are allowed with parentheses at either end of the local-part; e.g. john.smith(comment)@example.com and (comment)john.smith@example.com are both equivalent to john.smith@example.com;

我使用的代码将不允许限制性的特殊字符，但将允许比这里的大多数答案更多的选项。我更喜欢更宽松的验证，而不是谨慎的错误。

if enteredText.contains("..") || enteredText.contains("@@") 
   || enteredText.hasPrefix(".") || enteredText.hasSuffix(".con"){
       return false
}

let emailFormat = "[A-Z0-9a-z.!#$%&'*+-/=?^_`{|}~]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"
let emailPredicate = NSPredicate(format:"SELF MATCHES %@", emailFormat)     
return emailPredicate.evaluate(with: enteredText)

因为现在有这么多奇怪的顶级域名，我不再检查顶级域名的长度…

以下是我使用的方法:

extension String {

    func isEmail() -> Bool {
        let emailRegEx = "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$"
        return NSPredicate(format:"SELF MATCHES %@", emailRegEx).evaluateWithObject(self)
    } 
}