How to write to local Application Support directory on OS X - swift

Question

I'm writing a Swift app for OS X whose primary purpose is to read data from a usb device plugged into the computer and upload it to our services layer for analyzation and storage. The app is meant to be usable by any user that has an account on the Mac it is installed on.
For support and further analytical purposes, the app is also required to include its install id, a UUID generated during the first launch of the application, in every upload. This allows our support team to associate an installation instance of our app with the set of users who have access to it so that troubleshooting and data collection is more accurate and precise.
In my app, I'm storing the install id in a file and trying to store that file in a central location, the local Application Support directory.
More specifically, I would like to store it at the following location:
Macintosh HD/Library/Application Support/MyApp/installId/installId.txt.
This is how I try save files in the Application Support directory:
var installId = String()
let fileManager = FileManager.default
var isDir: ObjCBool = false
if let appSupportDirectory = fileManager.urls(for: .applicationSupportDirectory, in: .localDomainMask).first {
let installIdDirectory = appSupportDirectory.appendingPathComponent(Bundle.main.bundleIdentifier ?? "MyApp").appendingPathComponent("installId")
let installIdFile = installIdDirectory.appendingPathComponent("installId.txt")
do {
if fileManager.fileExists(atPath: installIdFile.path, isDirectory: &isDir) {
if !isDir.boolValue {
let data = try String.init(contentsOf: installIdFile)
installId = String(data.split(separator: ":")[1])installId))")
}
else {
print("\nError: installId file appears to be a directory.")
}
}
else {
try fileManager.createDirectory(at: installIdDirectory, withIntermediateDirectories: true, attributes: nil)
let pendingInstallId = "installId:\(UUID())"
try pendingInstallId.write(to: installIdFile, atomically: false, encoding: String.Encoding.utf8)
installId = pendingInstallId
}
} catch {
print("\nError: \(error.localizedDescription)")
}
}
else {
print("\nError: Could not find Application Support Directory.")
}
When I run my app, I receive the following error:
You don't have permission to save the file "installId" in the folder "MyApp".
The error does not occur; however, if I choose to store my file in the Application Support directory in the user domain mask. The file containing the install id is created and stored in a folder called MyApp within my user Application Support directory.
I've tried searching for a solution to my problem, but it has not been too fruitful. Some posts claim that the directory I'm trying to store my file in is reserved for apps with admin privileges (source 1) while others claim i should instead be using the Application Support directory in the user domain mask for such tasks (source 2). However, I need this file to be accessible to any user who has an account on the Mac that the app is installed on, so the local domain masks' Application Support directory seems to be a better fit for this scenario.
Could someone help me out or point me in the right direction? How can I save data to this directory? If I can't feasibly do so, is there another central location that I can do it where a user is unlikely to venture into and delete that data?
Thanks in advance!

Answer 1

The directory /Library/Application Support/ belongs to root. You can see that in a Terminal by typing:
$ ls -al /Library | grep Appl*
drwxr-xr-x 15 root admin 480 Jan 4 16:10 Application Support
To write to that directory your App needs root privileges. Refer to Apple Documentation to securely implement this. The Apple documentation mentions authopen which seems reasonable to create a file in the support folder at the first run of your App.