这段代码只是修复了@CrimsonX回答的错误:

 public static T FindChild<T>(DependencyObject parent, string childName)
       where T : DependencyObject
    {    
      // Confirm parent and childName are valid. 
      if (parent == null) return null;

      T foundChild = null;

      int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
      for (int i = 0; i < childrenCount; i++)
      {
        var child = VisualTreeHelper.GetChild(parent, i);
        // If the child is not of the request child type child
        T childType = child as T;
        if (childType == null)
        {
          // recursively drill down the tree
          foundChild = FindChild<T>(child, childName);

          // If the child is found, break so we do not overwrite the found child. 
          if (foundChild != null) break;
        }
        else if (!string.IsNullOrEmpty(childName))
        {
          var frameworkElement = child as FrameworkElement;
          // If the child's name is set for search
          if (frameworkElement != null && frameworkElement.Name == childName)
          {
            // if the child's name is of the request name
            foundChild = (T)child;
            break;
          }

 // recursively drill down the tree
          foundChild = FindChild<T>(child, childName);

          // If the child is found, break so we do not overwrite the found child. 
          if (foundChild != null) break;


        else
        {
          // child element found.
          foundChild = (T)child;
          break;
        }
      }

      return foundChild;
    }  

你只需要继续递归调用方法，如果类型匹配，但名称不匹配(这发生在你传递FrameworkElement作为T时)，否则它将返回null，这是错误的。

我可能只是在重复其他人，但我确实有一段漂亮的代码，它用FindChild()方法扩展了DependencyObject类，该方法将按类型和名称获取子对象。只是包含和使用。

public static class UIChildFinder
{
    public static DependencyObject FindChild(this DependencyObject reference, string childName, Type childType)
    {
        DependencyObject foundChild = null;
        if (reference != null)
        {
            int childrenCount = VisualTreeHelper.GetChildrenCount(reference);
            for (int i = 0; i < childrenCount; i++)
            {
                var child = VisualTreeHelper.GetChild(reference, i);
                // If the child is not of the request child type child
                if (child.GetType() != childType)
                {
                    // recursively drill down the tree
                    foundChild = FindChild(child, childName, childType);
                    if (foundChild != null) break;
                }
                else if (!string.IsNullOrEmpty(childName))
                {
                    var frameworkElement = child as FrameworkElement;
                    // If the child's name is set for search
                    if (frameworkElement != null && frameworkElement.Name == childName)
                    {
                        // if the child's name is of the request name
                        foundChild = child;
                        break;
                    }
                }
                else
                {
                    // child element found.
                    foundChild = child;
                    break;
                }
            }
        }
        return foundChild;
    }
}

希望对你有用。

试试这个

<TextBlock x:Name="txtblock" FontSize="24" >Hai Welcom to this page
</TextBlock>

后面的代码

var txtblock = sender as Textblock;
txtblock.Foreground = "Red"

您还可以使用FrameworkElement.FindName(string)按名称查找元素。

考虑到:

<UserControl ...>
    <TextBlock x:Name="myTextBlock" />
</UserControl>

在代码隐藏文件中，你可以这样写:

var myTextBlock = (TextBlock)this.FindName("myTextBlock");

当然，因为它是使用x:Name定义的，所以您可以只引用生成的字段，但是您可能希望动态而不是静态地查找它。

这种方法也可用于模板，其中命名项出现多次(每次使用模板一次)。

我找不到@CrimsonX或@Drew Noakes方法的控件，因为我的ControlTemplate位于一个单独的XAML文件中。 我用下面的方法找到了控件:

private Image backImage;
private void Diagram_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
    // here is the example of the ControlTemplate declaration
    //<ControlTemplate x:Key="DiagramControlTemplate1" TargetType="{x:Type Diagram}">
    var ctrlTemplate = (ControlTemplate)FindResource("DiagramControlTemplate1");
    // diagram is the x:Name of TemplatedControl and, "backImage" is the name of control that I want to find.
    var imageControl = ctrlTemplate.FindName("backImage", diagram);
    if (imageControl != null)
    {
        this.backImage = (Image)imageControl;
    }
}

这对我很有用。

要从代码中找到给定类型的祖先，您可以使用:

[CanBeNull]
public static T FindAncestor<T>(DependencyObject d) where T : DependencyObject
{
    while (true)
    {
        d = VisualTreeHelper.GetParent(d);

        if (d == null)
            return null;

        var t = d as T;

        if (t != null)
            return t;
    }
}

这个实现使用迭代而不是递归，可以稍微快一点。

如果你使用的是c# 7，这段代码可以略短:

[CanBeNull]
public static T FindAncestor<T>(DependencyObject d) where T : DependencyObject
{
    while (true)
    {
        d = VisualTreeHelper.GetParent(d);

        if (d == null)
            return null;

        if (d is T t)
            return t;
    }
}