Excel VBA File Dialog on a Mac

I’ve been creating Microsoft VBAs for years to solve different problems ranging from Finance to Engineering. These VBAs have been developed and hosted on Windows platforms using different versions of Microsoft Office products. Recently I had a VBA requirement where the client used Excel (365) on a Mac. For tis application the key differences between the two products/OSs were:

  • No userform development UI on Mac
  • Different file dialog
  • Full path filename parsing

To solve the the userform development UI issue, I just developed the userform on Windows. When the VBA executed on the Mac the userform was properly displayed without any issues. Any changes to the userform had to be done on a Windows platform.

The second problem was more difficult and required some research. Prevously I’ve accessed files using the Application.FileDialog function with the msoFileDialogFilePicker parameters. It’s straight forward and I have used this code many times. A code segment is shown below.

'Display a Dialog Box that allows to select a single file.
'The path for the file picked will be stored in fullpath variable
With Application.FileDialog(msoFileDialogFilePicker)
    'Makes sure the user can select only one file
    .AllowMultiSelect = False
    'Filter to just the following types of files to narrow down selection options
    .Filters.Add "CSV/CRC Files", "*.csv; *.crc", 1
    'Show the dialog box
    .Show
        
    'Store in fullpath variable if file selected
    If .SelectedItems.Count <> 0 Then
        fullpath = .SelectedItems.Item(1)
    Else
        MsgBox ("No file selected. Exiting program...")
        Exit Sub
    End If
End With

The problem is Application.FileDialog is not supported by Excel on the MacOS. I am thankful someone else had already solved this problem using an Applescript. I was able to reuse the posted script without any modifications. I created a function for each operating system to create a file dialog window and return the user selected file. On a Mac, if the user doesn’t select a file, the string “-128” (error code userCanceledErr) is returned. So the Windows function also returns “-128” when the user doesn’t select a file.

Function BrowseMac(mypath As String) As String
  Dim sMacScript As String
  
  sMacScript = "set applescript's text item delimiters to "","" " & vbNewLine & _
    "try " & vbNewLine & _
    "set theFiles to (choose file " & _
    "with prompt ""Please select a file or files"" default location alias """ & _
    mypath & """ multiple selections allowed false) as string" & vbNewLine & _
    "set applescript's text item delimiters to """" " & vbNewLine & _
    "on error errStr number errorNumber" & vbNewLine & _
    "return errorNumber " & vbNewLine & _
    "end try " & vbNewLine & _
    "return theFiles"
  BrowseMac = MacScript(sMacScript)
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Function BrowseWin() As String
    'Display a Dialog Box that allows to select a single file.
    'The path for the file picked will be stored in fullpath variable
    With Application.FileDialog(msoFileDialogFilePicker)
        'Makes sure the user can select only one file
        .AllowMultiSelect = False
        'Filter to just the following types of files to narrow down selection options
        .Filters.Add "Text Stock Files", "*.txt, 1"
        .Title = "Select Input Stock File"
        'Show the dialog box
        .Show
        
        'Store in fullpath variable if file selected
        If .SelectedItems.Count <> 0 Then
            BrowseWin = .SelectedItems.Item(1)
        Else
            BrowseWin = "-128"  ' what Mac OS returns when file is not selected
        End If
    End With
End Function

Since I was developing on Windows 10 and testing using both operating systems, I used Application.OperatingSystem to determine the host OS to call the appropriate routine. On MacOS Application.OperatingSystem includes “Macintosh” in the returned string. The call to the Mac file browser also uses an Applescript to the provide the documents folder directory path.

' determine OS and get input file via dialog box
theOS = Application.OperatingSystem
If (InStr(1, theOS, "Macintosh", vbTextCompare) = 0) Then   ' not Mac
    ' Windows Version
    fullFilename = BrowseWin
    fileName = getWINFName(fullFilename)
Else
    ' Mac Version
    fullFilename = BrowseMac(MacScript("return (path to documents folder) as String"))
    fileName = getMACFName(fullFilename)
End If
    
' check for a good file name
If fullFilename = "-128" Then
    MsgBox ("File not selected, no action taken.")
    Exit Sub
End If

The returned filename has the full path name. For this application I wanted to capture the filename only. So another difference between the operating sytsem is Windows uses the “\” character and MacOS used the “:” character to separate the path.

Function getWINFName(pf) As String: getWINFName = Mid(pf, InStrRev(pf, "\") + 1): End Function
Function getMACFName(pf) As String: getMACFName = Mid(pf, InStrRev(pf, ":") + 1): End Function

Working with the input file was the same for both Windows 10 and MacOS 10. Below is a small code snippet showing the opening the file, reading text line, and closing the file once finsihed.

Open fullFilename For Input As #1
Do Until EOF(1)
    ' get input record and separate items
    ' record data time, open, high, low, close, [volume]
    Line Input #1, textLine             ' input record
    inputSplit = Split(textLine, ",")   ' split on '

    < good code stuff >

Loop
Close #1

So my first experience developing an Excel VBA for MacOS had small, but solvable technical hurdles, which were solved by using a good search engine and leveraging other develper’s code.

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