如何在 ListView xamarin 上返回已处理的集合

Question

我想检查 if 语句，并且只想显示在列表视图上检查的这些值。

`  public void MarkerPressed2()
        {
            MessagingCenter.Subscribe<object, IEnumerable<AlertLevelOnClick>>(this, "PinInfo", (sender, arg) =>
            {
                lstLevel2.ItemsSource = arg;

                var listAlert = new List<AlertLevelOnClick>();

                foreach (var item in arg)
                {
                    
                    var currentData = new AlertLevelOnClick() {
                        dateForecastOnClick = item.dateForecastOnClick,
                        levelForecastOnClick = item.levelForecastOnClick

                    };

                    listAlert.Add(currentData);

                   

                    if (item.levelForecastOnClick == 1)
                    {
                        //how to return every rows on arg or on listview lstLevel2.ItemsSource = arg; with checked
                        //item.levelForecastOnClick and item.dateForecastOnClick on the listView like
                        var test = 5;

                    }
                    else if (item.levelForecastOnClick == 2)
                    {
                         //how to return every rows on arg or on listview lstLevel2.ItemsSource = arg; with checked
                        //item.levelForecastOnClick and item.dateForecastOnClick on the listView like 
                    }
                }
            });

           
        }

使用此代码：lstLevel2.ItemsSource = arg; 我填充了列表视图，但我想先检查 levelForecastOnClick == 1 是否只显示值为 1 和他的日期dateForecastOnClick

如何在 lstLevel2.ItemsSource 上返回检查 arg 集合？

Answer 1

// create an empty list
var listAlert = new List<AlertLevelOnClick>();

foreach (var item in arg)
{
   // if an item meets whatever conditions you want to test for
   if (item.levelForecastOnClick == 1 && ...)
   {
      // add it to the list
      listAlert.Add(item);
   }
}

// assign your filtered list to the ListView ItemsSource             
lstLevel2.ItemsSource = listAlert;