Seeking a Reliable Way to Refresh Finder for Custom Folder Icon Changes in a Sandboxed App

I've noticed that the AppleScript update command seems to force the kind of complete refresh I need:

So, what this actually does is technically documented, though the source is more than a little obscure. From the Files.h header doc for the long deprecated "FNNotify" API:

 *  Discussion:
 *    FNNotify is used to notify system clients (such as the Finder) of
 *    modifications to the contents of a directory, specifically
 *    addition or removal of files or folders from the directory. The
 *    Finder and other system clients will refresh their views of the
 *    specified directory when they receive the change notification.
 *    FNNotify is not meant to notify the Finder of changes to a
 *    specific file (for example, changes to a file's type or creator);
 *    for that purpose, use a kAESync AppleEvent sent to the Finder.

kAESync is defined in the equally obscure "FinderRegistry.h", inside the Carbon framework:

/*
   The old Finder Event suite was 'FNDR'
   The new suite is 'fndr'
*/
enum {
  kAEFinderSuite                = 'fndr'
};

/*
  //////////////////////////////////////
   Finder Events
  //////////////////////////////////////
*/
enum {
  kAECleanUp                    = 'fclu',
  kAEEject                      = 'ejct',
  kAEEmpty                      = 'empt',
  kAEErase                      = 'fera',
  kAEGestalt                    = 'gstl',
  kAEPutAway                    = 'ptwy',
  kAERebuildDesktopDB           = 'rddb',
  kAESync                       = 'fupd',
  kAEInterceptOpen              = 'fopn'
};

SO, that's the event you need to send. That leads to here:

However, the major roadblock is that I can't figure out how to reliably execute this from a sandboxed environment. I understand it likely requires specific scripting entitlements, but it's unclear which ones would be needed for this update command on a user-chosen folder, or if it's even permissible for the App Store.

What have you actually tried here? I haven't tested this in any detail but, as far as I can tell, kAEFinderSuite/kAESync is one of the "safe" AppleEvent that your app should be allowed to send without any additional configuration.

__
Kevin Elliott
DTS Engineer, CoreOS/Hardware

Hi there, Thank you very much for your response. Unfortunately, I am still unable to refresh the icon. I don't have much experience, so it may just be a small oversight. I tried to prompt the method because I couldn't find any documentation. This is my final solution.

I don't get any errors, but the icon still does not refresh. (kAESync AppleEvent sent successfully)

Test code

//  ContentView.swift
//  test refresh folder icon

import SwiftUI
import AppKit
import Carbon

struct ContentView: View {
    @State private var selectedFolder: URL?
    @State private var statusMessage: String = "No folder chosen"

    var body: some View {
        VStack(spacing: 16) {
            Text(statusMessage)
                .frame(maxWidth: .infinity, alignment: .leading)
                .padding(.horizontal)

            Button("Select Folder…", action: selectFolder)

            Button("Apply Test Icon & Refresh Finder", action: applyIcon)
                .disabled(selectedFolder == nil)
        }
        .padding()
        .frame(minWidth: 380, minHeight: 160)
    }

    // MARK: - Actions

    private func selectFolder() {
        let panel = NSOpenPanel()
        panel.canChooseFiles = false
        panel.canChooseDirectories = true
        panel.allowsMultipleSelection = false
        panel.prompt = "Choose"

        if panel.runModal() == .OK, let url = panel.url {
            selectedFolder = url
            statusMessage = "Selected: \(url.path)"
        }
    }

    private func applyIcon() {
        guard let folderURL = selectedFolder else { return }

        // For sandboxed apps, we must start accessing the security-scoped resource before use.
        guard folderURL.startAccessingSecurityScopedResource() else {
            statusMessage = "❌ Failed to access folder. Check sandbox entitlements."
            return
        }
        defer { folderURL.stopAccessingSecurityScopedResource() }

        // Simple colored square icon
        let iconSize = CGFloat(512)
        let icon = NSImage(size: NSSize(width: iconSize, height: iconSize), flipped: false) { rect in
            NSColor.systemOrange.setFill()
            rect.fill()
            return true
        }

        do {
            try NSWorkspace.shared.setIcon(icon, forFile: folderURL.path, options: [])
            sendKAESyncEvent(for: folderURL)
            statusMessage = "Icon updated successfully"
        } catch {
            statusMessage = "❌ Failed: \(error.localizedDescription)"
        }
    }

    // MARK: - DTS Engineer suggested kAESync AppleEvent

    private func sendKAESyncEvent(for url: URL) {
        let finderDescriptor = NSAppleEventDescriptor(bundleIdentifier: "com.apple.finder")
        
        // Create the AppleEvent for kAEFinderSuite/kAESync ('fndr'/'fupd')
        let appleEvent = NSAppleEventDescriptor(eventClass: AEEventClass(0x666e6472), // 'fndr'
                                                eventID: AEEventID(0x66757064),   // 'fupd'
                                                targetDescriptor: finderDescriptor,
                                                returnID: AEReturnID(kAutoGenerateReturnID),
                                                transactionID: AETransactionID(kAnyTransactionID))
        
        // Set the direct object parameter to the folder URL
        let fileDesc = NSAppleEventDescriptor(fileURL: url)
        appleEvent.setDescriptor(fileDesc, forKeyword: keyDirectObject)

        // Send the AppleEvent
        do {
            _ = try appleEvent.sendEvent(options: [.noReply], timeout: 1.0)
            NSLog("kAESync AppleEvent sent successfully")
        } catch {
            NSLog("kAESync AppleEvent failed: \(error.localizedDescription)")
        }
    }
}

#Preview {
    ContentView()
}

Question

1. Do you have any idea what might be causing the issue?
2. Could you please provide more information?

Many thanks for any insight!