ios - 电子邮件验证不适用于 textField shouldChangeCharactersInRange

Question

您好，我想在用户在文本字段中输入文本时验证电子邮件地址。当错误的电子邮件然后显示警报并返回否以留在电子邮件文本字段中时，它正在处理返回和文本字段结束编辑但不处理文本字段 shouldChangeCharactersInRange。如果有人知道如何做，请分享它，请提前致谢。这是我用于验证的示例代码作为返回

- (void)textFieldDidEndEditing:(UITextField *)textField
{
    activeTextfield=textField;
    if(activeTextfield==txtCon1Email || activeTextfield==txtCon1SecondMail ||   activeTextfield==txtCon2Email || activeTextfield==txtCon2SecondMail)
  {
     NSString *emailReg = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
     NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailReg];

     if ([emailTest evaluateWithObject:textField.text] == NO)
      {

        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"OTS" message:@"Please enter valid email address." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];



        isvalidemail=NO;


    }
    else
        isvalidemail=YES;

 }
}

但我想在用户输入文本时执行此操作

Answer 1

对于您的情况，这可能就足够了:只需尝试使用 textFieldDidEndEditing 委托(delegate):

-(BOOL)textFieldShouldEndEditing:(UITextField *)textField{
    if ([textField.text length]==0 || [self validateEmailWithString:textField.text]) {
        [textField resignFirstResponder];

    }else{
       [[[UIAlertView alloc] initWithTitle:@"OTS" message:@"Please enter valid email address." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]show];

        [textField becomeFirstResponder];
        return NO;
    }
    return YES;
}

- (BOOL)validateEmailWithString:(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];
}