Question

我正在使用xamarin.forms开发企业应用程序。已经过去几天，ListView的内存泄漏问题对我来说成了一场噩梦。为简单起见，我将尝试用示例代码进行解释。

XAML页码 - 包含ListView和两个按钮的页面（添加和删除）

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:ListViewTest"
             x:Class="ListViewTest.MainPage">
  <Grid>
    <Grid.RowDefinitions>
      <RowDefinition Height="10*" />
      <RowDefinition Height="1*"/>
      <RowDefinition Height="1*"/>
    </Grid.RowDefinitions>
    <ListView Grid.Row="0" BackgroundColor="White" x:Name ="ItemsListView">
      <ListView.ItemTemplate>
        <DataTemplate >
          <TextCell TextColor="Black" Text="{Binding ItemText}" 
                    DetailColor="Black" Detail="{Binding ItemDetail}" />
        </DataTemplate>
      </ListView.ItemTemplate>
    </ListView>
    <Button Grid.Row="1" Text="Add" Clicked="AddItemClicked"/>
    <Button Grid.Row="2" Text="Remove" Clicked="RemoveItemClicked"/>
  </Grid>
</ContentPage>

C＃代码背后 - 只需在集合中添加和删除对象。

public partial class MainPage : ContentPage
    {
        ObservableCollection<SampleData> itemsListCollection;
        public MainPage()
        {
            InitializeComponent();
            itemsListCollection = new ObservableCollection<SampleData>();
            ItemsListView.ItemsSource = itemsListCollection;
        }
        void AddItemClicked(object sender, EventArgs e)
        {
            SampleData data = new SampleData();
            data.ItemText = "An Item";
            data.ItemDetail = "Item - " + (itemsListCollection.Count + 1).ToString();
            itemsListCollection.Add(data);
        }

        void RemoveItemClicked(object sender, EventArgs e)
        {
            SampleData item = (SampleData)ItemsListView.SelectedItem;
            if (item != null)
            {
                itemsListCollection.Remove(item);
            }
        }

    }

数据类 - 只有两个属性

class SampleData
    {
        public event PropertyChangedEventHandler PropertyChanged;    
        private string itemText;
        public string ItemText
        {
            get
            {
                return itemText;
            }
            set
            {
                itemText = value;
                NotifyPropertyChanged("ItemText");
            }
        }
        private string itemDetail;
        public string ItemDetail
        {
            get
            {
                return itemDetail;
            }
            set
            {
                itemDetail = value;
                NotifyPropertyChanged("ItemDetail");
            }
        }
        private void NotifyPropertyChanged(string propName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propName));
            }
        }
    }

添加按钮 - 将项目添加到ListView
删除按钮 - 从ListView中删除项目

问题 -

添加一些项目列表。
删除少数或全部。
所有以前添加的 SampleData 对象即使在所有项目都存在之后仍保留在内存中已使用“删除”按钮删除。

Image - Memory Snapshot of original application
Image - Detailed Memory Snapshot of sample application

Xamarin.Forms ListView内存泄漏

0 个答案: