Iteratively open files in a folder and run a subroutine - excel

Question

I'm attempting to iteratively open every Excel file in a selected folder and then run a series of subroutines on each file. I originally developed the macro (lazily named Main) that opens a single file and performs the appropriate actions - this sub works just fine as far as I can tell.
I'm now working on building a sub called FolderPicker that will open each file in a selected folder and then run the Main sub.
Currently, I have this code, adapted from https://www.thespreadsheetguru.com/the-code-vault/2014/4/23/loop-through-all-excel-files-in-a-given-folder
Sub FolderPicker()
Dim wb As Workbook
Dim myPath As String
Dim MyFile As String
Dim myExtension As String
Dim FldrPicker As FileDialog
'Optimize Macro Speed
Application.ScreenUpdating = False
Application.EnableEvents = False
Application.Calculation = xlCalculationManual
'Retrieve Target Folder Path From User
Set FldrPicker = Application.FileDialog(msoFileDialogFolderPicker)
With FldrPicker
.Title = "Select A Target Folder"
.AllowMultiSelect = False
If .Show <> -1 Then GoTo NextCode
myPath = .SelectedItems(1) & "\"
End With
'In Case of Cancel
NextCode:
myPath = myPath
If myPath = "" Then GoTo ResetSettings
'Target File Extension (must include wildcard "*")
myExtension = "*.xls*"
'Target Path with Ending Extention
MyFile = Dir(myPath & myExtension)
'Loop through each Excel file in folder
Do While MyFile <> ""
'Set variable equal to opened workbook
Set wb = Workbooks.Open(Filename:=myPath & MyFile)
vFileName = myPath & MyFile
'Ensure Workbook has opened before moving on to next line of code
DoEvents
'Run main sub
main
'Ensure main has completed
DoEvents
'Save and Close Workbook
wb.Activate
wb.Close savechanges:=False
'Ensure Workbook has closed before moving on to next line of code
DoEvents
'Get next file name
MyFile = Dir
Loop
'Message Box when tasks are completed
MsgBox "Task Complete!"
ResetSettings:
'Reset Macro Optimization Settings
Application.EnableEvents = True
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
End Sub
The beginning of this macro runs just fine, the folder dialog box works, and it opens the first file. However, the MyFile = Dir line directly proceeding Loop doesn't seem to be working - it evaluates to a null value and then the sub ends. I've verified that there are multiple files in the folder.
For reference, vFileName is a publicly declared variant that's used in Main.
Any suggestions?

Answer 1

You cannot use nested Dir() loops, so if main also uses Dir() then you'll need to take a different approach, such as adding all the matches from the outer Dir() to a Collection and then looping over that to call main on each match.