UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"新建文件夹" message:@"" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil];

    [alert setAlertViewStyle:UIAlertViewStylePlainTextInput];

    UITextField *txtName = [alert textFieldAtIndex:0];

    txtName.placeholder = @"请输入名称";

    [alert show];

#pragma mark - 点击代理

-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{

    if (buttonIndex == 1) {

        UITextField *txt = [alertView textFieldAtIndex:0];

        ／／获取txt内容即可

    }

}