对@和做一个简单的测试。然后发一封确认邮件。

考虑一下:

世界上有一半的人使用非ascii字符。 正则表达式是缓慢和复杂的。顺便说一下，至少检查字符/字母/Unicode范围，而不是az。 因为RFC规则和相应的正则表达式太复杂，所以无法进行完全验证。

我用的是这个基本的检查:

// similar to https://softwareengineering.stackexchange.com/a/78372/22077
import Foundation

/**
 Checks that
 - length is 254 or less (see https://stackoverflow.com/a/574698/412916)
 - there is a @ which is not the first character
 - there is a . after the @
 - there are at least 4 characters after the @
*/
func isValidEmail(email: String) -> Bool {
    guard email.count <= 254 else { 
        return false 
    }
    let pos = email.lastIndex(of: "@") ?? email.endIndex
    return (pos != email.startIndex)
        && ((email.lastIndex(of: ".") ?? email.startIndex) > pos) 
        && (email[pos...].count > 4)
}

print(isValidEmail(email: "アシッシュ@ビジネス.コム")) // true

请注意,

它比regex和NSDataDetector快得多。 它正确地报告以下内容为有效:

Håkan.Söderström@malmö.se"
punnycode@XN--0ZWM56D.XN--HGBK6AJ7F53BBA"
试@例子.测试.مثال.آزمایشی"
foo.bar+something@blah.com"
m@foo.co.uk

它错误地将以下内容报告为无效——因为它们实际上是有效的，但可能是用户错误的产物:

a @ b
a@b

相关:

电子邮件地址验证应该走多远? 在线电子邮件检查:https://isemail.info/

创建简单的扩展:

extension NSRegularExpression {

    convenience init(pattern: String) {
        try! self.init(pattern: pattern, options: [])
    }
}

extension String {

    var isValidEmail: Bool {
        return isMatching(expression: NSRegularExpression(pattern: "^[A-Z0-9a-z\\._%+-]+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2,4}$"))
    }

    //MARK: - Private

    private func isMatching(expression: NSRegularExpression) -> Bool {
        return expression.numberOfMatches(in: self, range: NSRange(location: 0, length: characters.count)) > 0
    }
}

例子:

"b@bb.pl".isValidEmail //true
"b@bb".isValidEmail //false

你可以扩展以下扩展到任何你需要的:isValidPhoneNumber, isValidPassword等…

我会使用npredicate:

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)
}

对于Swift 3.0之前的版本:

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)
}

对于Swift 1.2之前的版本:

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

    if let emailPred = NSPredicate(format:"SELF MATCHES %@", emailRegEx) {
        return emailPred.evaluateWithObject(email)
    }
    return false
}

以下是目前Swiftmailer中一个非常简单的方法。其他大多数答案都是老掉牙的。

根据Swiftmailer文档: https://swiftmailer.symfony.com/docs/messages.html#quick-reference

use Egulias\EmailValidator\EmailValidator;
use Egulias\EmailValidator\Validation\RFCValidation;

$validator = new EmailValidator();
$validator->isValid("example@example.com", new RFCValidation()); //true

在我看来，这是迄今为止最简单、最健壮的方法。只需通过Composer安装egalias \EmailValidator库，它应该已经作为SwiftMailer的依赖项引入了。

在Swift 4.2和Xcode 10.1中

//Email validation
func isValidEmail(email: String) -> Bool {
    let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"
    var valid = NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluate(with: email)
    if valid {
        valid = !email.contains("Invalid email id")
    }
    return valid
}

//Use like this....
let emailTrimmedString = emailTF.text?.trimmingCharacters(in: .whitespaces)
if isValidEmail(email: emailTrimmedString!) == false {
   SharedClass.sharedInstance.alert(view: self, title: "", message: "Please enter valid email")
}

如果你想使用SharedClass。

//This is SharedClass
import UIKit
class SharedClass: NSObject {

static let sharedInstance = SharedClass()

//Email validation
func isValidEmail(email: String) -> Bool {
    let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"
    var valid = NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluate(with: email)
    if valid {
        valid = !email.contains("Invalid email id")
    }
    return valid
}

private override init() {

}
}

并调用这样的函数....

if SharedClass.sharedInstance. isValidEmail(email: emailTrimmedString!) == false {
   SharedClass.sharedInstance.alert(view: self, title: "", message: "Please enter correct email")
   //Your code here
} else {
   //Code here
}

或者你可以扩展可选文本UITextField:

使用方法:

if  emailTextField.text.isEmailValid() {
      print("email is valid")
}else{
      print("wrong email address")
}

扩展:

extension Optional where Wrapped == String {
    func isEmailValid() -> Bool{
        guard let email = self else { return false }
        let emailPattern = "[A-Za-z-0-9.-_]+@[A-Za-z0-9]+\\.[A-Za-z]{2,3}"
        do{
            let regex = try NSRegularExpression(pattern: emailPattern, options: .caseInsensitive)
            let foundPatters = regex.numberOfMatches(in: email, options: .anchored, range: NSRange(location: 0, length: email.count))
            if foundPatters > 0 {
                return true
            }
        }catch{
            //error
        }
        return false
    }
}