查找子控件有以下几种方法
1.GetTemplateChild
2.FindName

GetTemplateChild

顾名思义GetTemplateChild通过名称查找控件,那么要查找的控件必须是通过实现
自定义ControlTemplate方式实现。
需要注意的是通过GetTemplateChild查找控件，必须在自定义控件内获取，如果在Winodw中使用该控件，在Window中是无法通过GetTemplateChild来查找该控件的。
如下我们自定义了一个控件CustomControl1

<Style TargetType="{x:Type controls:CustomControl1}">
        <Setter Property="BorderBrush" Value="Gray"/>
        <Setter Property="BorderThickness" Value="1"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type controls:CustomControl1}">
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                        <Grid Background="AliceBlue" Margin="5">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="Auto"/>
                            </Grid.RowDefinitions>
                            <TextBlock x:Name="ControlTitleName" Grid.Row="0" FontSize="16" Text="{Binding Title, RelativeSource={RelativeSource TemplatedParent}}"/>
                            <TextBlock x:Name="ControlTitleSummary" Grid.Row="1" FontSize="12" Text="{TemplateBinding Summary}" Opacity="0.8"/>
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

在CustomControl1.cs的实现文件中我们可以重载OnApplyTemplate函数内获取
ControlTitleName和ControlTitleSummary这两个TextBlock

GetTemplateChild("ControlTitleName") as TextBlock
GetTemplateChild("ControlTitleSummary") as TextBlock

FindName

该接口只能用于cs文件和xaml文件强关联的类中，比如像Window和自定义用户控件。
比如在Window.xaml中定义了名为WindowTestBlockName的TextBlock
<TextBlock Margin="5" Text="名称为TestBlockName" x:Name="WindowTestBlockName"/>
那么在Window.cs中就可以通过FindName来查找该TextBlock.

通过类型查找子控列表

/// <summary>
        /// 通过某种类型查找子控件列表
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="parentObj">某个父控件</param>
        /// <param name="typename">需要查找子控件类型</param>
        /// <returns>查找到的子控件列表</returns>
        public List<T> GetChildObjects<T>(DependencyObject parentObj, Type typename) where T : FrameworkElement
        {
            DependencyObject child = null;
            List<T> childList = new List<T>();

            for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(parentObj) - 1; i++)
            {
                child = VisualTreeHelper.GetChild(parentObj, i);

                if (child is T && (((T)child).GetType() == typename))
                {
                    childList.Add((T)child);
                }
                childList.AddRange(GetChildObjects<T>(child, typename));
            }
            return childList;
        }

调用方式
List<TextBlock> listButtons = GetChildObjects<TextBlock>(ParentGridName, typeof(TextBlock));

通过名称来查找子控件列表

/// <summary>
        /// 通过名称来查找子控件列表
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="parentObj">需要查找的父控件</param>
        /// <param name="name">需要查找的控件名称</param>
        /// <returns></returns>
        public T GetChildObject<T>(DependencyObject parentObj, string name) where T : FrameworkElement
        {
            DependencyObject child = null;
            T grandChild = null;

            for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(parentObj) - 1; i++)
            {
                child = VisualTreeHelper.GetChild(parentObj, i);

                if (child is T && (((T)child).Name == name | string.IsNullOrEmpty(name)))
                {
                    return (T)child;
                }
                else
                {
                    grandChild = GetChildObject<T>(child, name);
                    if (grandChild != null)
                        return grandChild;
                }
            }
            return null;
        }

调用
List<TextBlock> list2 = GetChildObjects<TextBlock>(ParentGridName, "SubName");

按名称查找子控件

/// <summary>
        /// 按名称查找子控件
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="parentObj">开始查找的父控件</param>
        /// <param name="name">需要查找控件名称</param>
        /// <returns></returns>
        public List<T> GetChildObjects<T>(DependencyObject parentObj, string name) where T : FrameworkElement
        {
            DependencyObject child = null;
            List<T> childList = new List<T>();

            for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(parentObj) - 1; i++)
            {
                child = VisualTreeHelper.GetChild(parentObj, i);

                if (child is T && (((T)child).Name == name | string.IsNullOrEmpty(name)))
                {
                    childList.Add((T)child);
                }
                childList.AddRange(GetChildObjects<T>(child, name));
            }
            return childList;
        }

调用
TextBlock sub = GetChildObject<TextBlock>(ParentGridName, "SubName");

按父控件名称查找父控件

/// <summary>
        /// 按父控件名称查找父控件
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="obj">锚点子控件</param>
        /// <param name="parentName">父控件名称</param>
        /// <returns>返回父控件</returns>
        public T GetParentObject<T>(DependencyObject obj, string parentName) where T : FrameworkElement
        {
            DependencyObject parent = VisualTreeHelper.GetParent(obj);

            while (parent != null)
            {
                if (parent is T && (((T)parent).Name == parentName | string.IsNullOrEmpty(parentName)))
                {
                    return (T)parent;
                }

                parent = VisualTreeHelper.GetParent(parent);
            }

            return null;
        }

调用
Grid sub2 = GetParentObject<Grid>(SubTextBlock, "ParentGridName");