objective-c 检测邮箱地址输入合法性

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