判断邮箱合法性

BOOL NSStringIsValidEmail(NSString *checkString)  
{  
    NString *stricterFilterString = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"; 
    NSString *laxString = @".+@.+\.[A-Za-z]{2}[A-Za-z]*";  
    NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;  
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];  
    return [emailTest evaluateWithObject:checkString];  
}

 转自:http://www.cocoachina.com/iphonedev/sdk/2011/0621/2960.html