VB.NET中如何在创建控件的Sub之外移除该控件

我编写了一段代码，每次运行时都会创建一个PictureBox，该代码运行正常：

Public Sub BtnHit_Click(sender As Object, e As EventArgs) Handles BtnHit.Click
        
        Dim PicBoxNewCard As New PictureBox
        PicBoxNewCard.Width = 114
        PicBoxNewCard.Height = 166
        PicBoxNewCard.SizeMode = PictureBoxSizeMode.Zoom
        DrawCard(PicBoxNewCard)
        Me.Controls.Add(PicBoxNewCard)
        PicBoxNewCard.Location = New Point((257 + (57 * DrawnCardCounter)), 349)

但我希望通过点击按钮在创建这些PictureBox的Sub之外删除它们。我搜索过相关内容，尝试过创建类、面板等方法但都未成功，我知道Me.Controls.Remove(PicBoxNewCard)可以实现，但该代码仅在同一Sub中有效。

方法1：用Panel统一管理卡片控件 #

这是最省心的方案，先在窗体上拖入一个Panel控件（命名为pnlCards），调整到合适的位置和尺寸，然后修改创建控件的代码，把卡片添加到Panel而非直接添加到窗体：

Public Sub BtnHit_Click(sender As Object, e As EventArgs) Handles BtnHit.Click
        
        Dim PicBoxNewCard As New PictureBox
        PicBoxNewCard.Width = 114
        PicBoxNewCard.Height = 166
        PicBoxNewCard.SizeMode = PictureBoxSizeMode.Zoom
        DrawCard(PicBoxNewCard)
        ' 将控件添加到Panel容器
        pnlCards.Controls.Add(PicBoxNewCard)
        PicBoxNewCard.Location = New Point((257 + (57 * DrawnCardCounter)), 349)
End Sub

删除时直接清空Panel的控件集合即可，同时记得释放资源避免内存泄漏：

Public Sub BtnRemoveCards_Click(sender As Object, e As EventArgs) Handles BtnRemoveCards.Click
        ' 先遍历释放所有PictureBox资源
        For Each ctrl As Control In pnlCards.Controls.OfType(Of PictureBox)().ToList()
            ctrl.Dispose()
        Next
        pnlCards.Controls.Clear()
End Sub

方法2：给PictureBox打标记后筛选删除 #

如果不想用Panel，可以在创建控件时给它设置独特的Tag属性，后续通过标记筛选目标控件：

Public Sub BtnHit_Click(sender As Object, e As EventArgs) Handles BtnHit.Click
        
        Dim PicBoxNewCard As New PictureBox
        PicBoxNewCard.Width = 114
        PicBoxNewCard.Height = 166
        PicBoxNewCard.SizeMode = PictureBoxSizeMode.Zoom
        ' 设置标记，标识这是卡片控件
        PicBoxNewCard.Tag = "CardPictureBox"
        DrawCard(PicBoxNewCard)
        Me.Controls.Add(PicBoxNewCard)
        PicBoxNewCard.Location = New Point((257 + (57 * DrawnCardCounter)), 349)
End Sub

删除时遍历窗体控件，筛选出带标记的PictureBox并移除：

Public Sub BtnRemoveCards_Click(sender As Object, e As EventArgs) Handles BtnRemoveCards.Click
        ' 转成ToList避免遍历过程中集合变化报错
        For Each picBox As PictureBox In Me.Controls.OfType(Of PictureBox)().ToList()
            If picBox.Tag IsNot Nothing AndAlso picBox.Tag.ToString() = "CardPictureBox" Then
                Me.Controls.Remove(picBox)
                picBox.Dispose() ' 必须释放资源
            End If
        Next
End Sub

方法3：用全局集合存储创建的PictureBox #

在窗体类的顶部声明一个全局List，专门保存所有创建的卡片控件：

' 窗体类的全局变量
Private cardPictureBoxes As New List(Of PictureBox)()

修改创建代码，把新生成的PictureBox加入集合：

Public Sub BtnHit_Click(sender As Object, e As EventArgs) Handles BtnHit.Click
        
        Dim PicBoxNewCard As New PictureBox
        PicBoxNewCard.Width = 114
        PicBoxNewCard.Height = 166
        PicBoxNewCard.SizeMode = PictureBoxSizeMode.Zoom
        DrawCard(PicBoxNewCard)
        Me.Controls.Add(PicBoxNewCard)
        PicBoxNewCard.Location = New Point((257 + (57 * DrawnCardCounter)), 349)
        ' 添加到全局集合
        cardPictureBoxes.Add(PicBoxNewCard)
End Sub

删除时直接遍历集合，逐个移除并释放资源：

Public Sub BtnRemoveCards_Click(sender As Object, e As EventArgs) Handles BtnRemoveCards.Click
        For Each picBox As PictureBox In cardPictureBoxes
            Me.Controls.Remove(picBox)
            picBox.Dispose()
        Next
        ' 清空集合
        cardPictureBoxes.Clear()
End Sub

内容的提问来源于stack exchange，提问作者goodscore