如何在警报视图IOS中创建两个文本字段

method:
//show alertview for file input
- (IBAction)showAddFiles:(id)sender {
    UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Enter File Details"
                                                      message:nil
                                                     delegate:self
                                            cancelButtonTitle:@"Cancel"
                                            otherButtonTitles:@"Add",nil];



    UITextField *textFieldDescription = [message textFieldAtIndex:0];
    textFieldDescription.placeholder = @"File Description : Ex. Acat Briefing";
    UITextField *textFieldFileName = [message textFieldAtIndex:1];
    textFieldFileName.placeholder = @"Exact File Name : Ex. acat.pdf";


    [message show];
}


//make sure file description is long enoguh
- (BOOL)alertViewShouldEnableFirstOtherButton:(UIAlertView *)alertView
{
    Nsstring *inputText = [[alertView textFieldAtIndex:0] text];

    if( [inputText length] <= 15 && [inputText length] >= 4)
    {
        return YES;
    }
    else
    {
        return NO;
    }
}

//handle add button
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    Nsstring *title = [alertView buttonTitleAtIndex:buttonIndex];
    if([title isEqualToString:@"Add"])
    {
        UITextField *fileDescription = [alertView textFieldAtIndex:0];
        UITextField *fileName = [alertView textFieldAtIndex:1];
        NSLog(@"Desc: %@\nName: %@",fileDescription.text,fileName.text);
    }
}

错误：

*由于未捕获的异常’NSinvalidargumentexception’终止应用程序,原因：’textFieldindex(0)超出了文本字段数组的范围’

为什么我会收到此错误,如何在警报视图中创建两个uitextfield？

=========工作解决方案===========
感谢下面的答案,当你只需要两个纯文本字段时

//show alertview for file input
- (IBAction)showAddFiles:(id)sender {
    UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Enter File Details"
                                                      message:nil
                                                     delegate:self
                                            cancelButtonTitle:@"Cancel"
                                            otherButtonTitles:@"Add",nil];



    [message setAlertViewStyle:UIAlertViewStyleLoginAndPasswordInput];
    UITextField *fileDescription = [message textFieldAtIndex:0];
    fileDescription.placeholder=@"Ex. acat.pdf";
    [[message textFieldAtIndex:1] setSecureTextEntry:NO];
    UITextField *fileName= [message textFieldAtIndex:1];
    fileName.placeholder=@"Ex. Acat Briefing";

    [message show];
}