Access a number of controls in a windows form using a loop

Imports System.Windows.Forms

Public Module ControlExtensions
    ''' <summary>
    ''' Get list of TextBox on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of TextBox or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function TextBoxList(pControl As Control) As List(Of TextBox)
        Return pControl.Descendants(Of TextBox)().ToList()
    End Function
    ''' <summary>
    ''' Get list of Label on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of Label or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function LabelList(pControl As Control) As List(Of Label)
        Return pControl.Descendants(Of Label)().ToList()
    End Function
    ''' <summary>
    ''' Get list of CheckBox on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of CheckBox or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function CheckBoxList(pControl As Control) As List(Of CheckBox)
        Return pControl.Descendants(Of CheckBox)().ToList()
    End Function
    ''' <summary>
    ''' Get list of DataGridView on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of DataGridView or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function DataGridViewList(pControl As Control) As List(Of DataGridView)
        Return pControl.Descendants(Of DataGridView)().ToList()
    End Function
    ''' <summary>
    ''' Get list of ComboBox on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of ComboBox or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function ComboBoxList(pControl As Control) As List(Of ComboBox)
        Return pControl.Descendants(Of ComboBox)().ToList()
    End Function
    ''' <summary>
    ''' Get list of ListBox on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of ListBox or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function ListBoxList(pControl As Control) As List(Of ListBox)
        Return pControl.Descendants(Of ListBox)().ToList()
    End Function
    ''' <summary>
    ''' Get list of DateTimePicker on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of DateTimePicker or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function DateTimePickerList(pControl As Control) As List(Of DateTimePicker)
        Return pControl.Descendants(Of DateTimePicker)().ToList()
    End Function
    ''' <summary>
    ''' Get list of PictureBox on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of PictureBox or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function PictureBoxList(pControl As Control) As List(Of PictureBox)
        Return pControl.Descendants(Of PictureBox)().ToList()
    End Function
    ''' <summary>
    ''' Get list of Panel on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of Panel or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function PanelList(pControl As Control) As List(Of Panel)
        Return pControl.Descendants(Of Panel)().ToList()
    End Function
    ''' <summary>
    ''' Get list of GroupBox on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of GroupBox or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function GroupBoxList(pControl As Control) As List(Of GroupBox)
        Return pControl.Descendants(Of GroupBox)().ToList()
    End Function
    ''' <summary>
    ''' Get list of ListView on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of ListView or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function ListViewList(pControl As Control) As List(Of ListView)
        Return pControl.Descendants(Of ListView)().ToList()
    End Function
    ''' <summary>
    ''' Get list of Button on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of Button or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function ButtonList(pControl As Control) As List(Of Button)
        Return pControl.Descendants(Of Button)().ToList()
    End Function
    <Runtime.CompilerServices.Extension>
    Public Function RadioButtonList(pControl As Control) As List(Of RadioButton)
        Return pControl.Descendants(Of RadioButton)().ToList()
    End Function
    ''' <summary>
    ''' Get selected RadioButton
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <param name="pChecked">True to get checked</param>
    ''' <returns>Get selected RadioButton</returns>
    <Runtime.CompilerServices.Extension>
    Public Function RadioButtonChecked(pControl As Control, Optional pChecked As Boolean = True) As RadioButton
        Return pControl.Descendants(Of RadioButton)().ToList().FirstOrDefault(Function(radioButton) radioButton.Checked = pChecked)
    End Function
    ''' <summary>
    ''' Get list of NumericUpDown on control
    ''' </summary>
    ''' <param name="pControl">Control to find controls on</param>
    ''' <returns>List of NumericUpDown or empty list</returns>
    <Runtime.CompilerServices.Extension>
    Public Function NumericUpDownList(pControl As Control) As List(Of NumericUpDown)
        Return pControl.Descendants(Of NumericUpDown)().ToList()
    End Function
    ''' <summary>
    ''' Get names of controls 
    ''' </summary>
    ''' <param name="pControls"></param>
    ''' <returns></returns>
    <Runtime.CompilerServices.Extension>
    Public Function ControlNames(pControls As IEnumerable(Of Control)) As String()
        Return pControls.Select(Function(c) c.Name).ToArray()
    End Function
    ''' <summary>
    ''' Is control a container
    ''' </summary>
    ''' <param name="pControl"></param>
    ''' <returns></returns>
    <Runtime.CompilerServices.Extension>
    Public Function IsContainer(pControl As Control) As Boolean
        Return pControl.HasChildren
    End Function
End Module

Enum SearchMethod
    StartsWith = 1
    EndsWith = 2
    Contains = 3
End Enum

Function GetAllControls(Of T As Control)(ctrl As Control, key As String, method As SearchMethod, Optional useTag As Boolean = True) As IEnumerable(Of T)
    ' TODO validate args
    Dim upperKey = key.ToUpper

    Dim searchPredicates() As Func(Of String, Boolean) = {
        Function(src, tgt) src.StartsWith(upperKey),
        Function(src, tgt) src.EndsWith(upperKey),
        Function(src, tgt) src.Contains(upperKey)
    }
    Dim ctrlSelector As Func(Of Control, String) = If(useTag, Function(c) c.Tag.ToString.ToUpper, Function(c) c.Name.ToUpper)

    Return GetAllControlsIterator(Of T)(ctrl, ctrlSelector, searchPredicates(CInt(method) - 1))
End Function

Private Iterator Function GetAllControlsIterator(Of T As Control)(ctrl As Control, ctrlSelector As Func(Of Control, String), searchPredicate As Func(Of String, Boolean)) As IEnumerable(Of T)
    For Each child In ctrl.Controls
        If searchPredicate(ctrlSelector(child)) AndAlso TypeOf child Is T Then Yield DirectCast(child, T)

        For Each grandChild In GetAllControlsIterator(Of T)(child, ctrlSelector, searchPredicate)
            Yield DirectCast(grandChild, T)
        Next
    Next
End Function