Medium - Bookmark user chosen directories in macOS sandbox

AppDelegate.swift

import Cocoa
import SwiftUI

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    
    var window: NSWindow!
    
    let bookMarkKey = "chosenDirBookmarkKey";
    
    func applicationDidFinishLaunching(_ aNotification: Notification) {
        if let bookMarkData = UserDefaults.standard.data(forKey: bookMarkKey) {
            do {
                var isStale = false;
                let bookMarkUrl = try URL(resolvingBookmarkData: bookMarkData, options: .withSecurityScope, relativeTo: nil, bookmarkDataIsStale: &isStale);
                
                if(!isStale) {
                    if(bookMarkUrl.startAccessingSecurityScopedResource()) {
                        enumerateFileAndDirectories(url: bookMarkUrl)
                        bookMarkUrl.stopAccessingSecurityScopedResource()
                    } else {
                        // Cannot access security scoped resource.
                    }
                } else {
                    // The bookmark is stale
                }
            } catch {
                // Error creating a URL from the bookmark
            }
        } else {
            // The bookmark does not yet existing UserDefaults
            askUserForDirectory()
        }
    }
    
    func askUserForDirectory() {
        let panel = NSOpenPanel();
        panel.canChooseDirectories = true;
        panel.canChooseFiles = false;
        panel.canCreateDirectories = false;
        panel.allowsMultipleSelection = false;
        
        panel.begin(completionHandler: { result in
            if(result == .OK) {
                
                do {
                    let bookmarkData = try panel.url!.bookmarkData(options: .withSecurityScope, includingResourceValuesForKeys: nil, relativeTo: nil)
                    
                    UserDefaults.standard.set(bookmarkData, forKey: self.bookMarkKey);
                    
                } catch {
                    // Error creating the bookmark
                }
                
                self.enumerateFileAndDirectories(url: panel.url!)
            } else {
                // Choosing a directory was not successful
            }
        })
    }
    
    func enumerateFileAndDirectories(url: URL) {
        if let enumerator = FileManager.default.enumerator(at: url, includingPropertiesForKeys: [.isRegularFileKey, .isDirectoryKey], options: [.skipsHiddenFiles, .skipsPackageDescendants]) {
            for case let fileURL as URL in enumerator {
                print(fileURL);
            }
        } else {
            // There was an error creating an enumerator
        }
    }
    
    func applicationWillTerminate(_ aNotification: Notification) {
        // Insert code here to tear down your application
    }
}

askUserForDirectory1.swift

func askUserForDirectory() {
    let panel = NSOpenPanel();
    panel.canChooseDirectories = true;
    panel.canChooseFiles = false;
    panel.canCreateDirectories = false;
    panel.allowsMultipleSelection = false;
    
    panel.begin(completionHandler: { result in
        if(result == .OK) {
            self.enumerateFileAndDirectories(url: panel.url!)
        } else {
            // Choosing a directory was not successful
        }
    })
}

askUserForDirectory2.swift

// ....askUserForDirectory()

panel.begin(completionHandler: { result in
    if(result == .OK) {
        do {
            let bookmarkData = try panel.url!.bookmarkData(options: .withSecurityScope, includingResourceValuesForKeys: nil, relativeTo: nil)  
            UserDefaults.standard.set(bookmarkData, forKey: self.bookMarkKey);        
        } catch {
            // Error creating the bookmark
        }
        
        self.enumerateFileAndDirectories(url: panel.url!)
    } else {
        // Choosing a directory was not successful
    }
})

checkForBookmark.swift

func applicationDidFinishLaunching(_ aNotification: Notification) {
    if let bookMarkData = UserDefaults.standard.data(forKey: bookMarkKey) {
        do {
            var isStale = false;
            let bookMarkUrl = try URL(resolvingBookmarkData: bookMarkData, options: .withSecurityScope, relativeTo: nil, bookmarkDataIsStale: &isStale);
            
            if(!isStale) {
                if(bookMarkUrl.startAccessingSecurityScopedResource()) {
                    enumerateFileAndDirectories(url: bookMarkUrl)
                    bookMarkUrl.stopAccessingSecurityScopedResource()
                } else {
                    // Cannot access security scoped resource.
                }
            } else {
                // The bookmark is stale
            }
        } catch {
            // Error creating a URL from the bookmark
        }
    } else {
        // The bookmark does not yet existing UserDefaults
        askUserForDirectory()
    }
}