Where can a sandboxed Mac app save files? - objective-c

Question

My Mac app is sandboxed and I need to save a file. Where do I save this file? I can't seem to find the specific place where this is allowed without using an open panel. This is how I do it on iOS:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [paths objectAtIndex:0];
What is the equivalent for the sandboxed directory on Mac?

Answer 1

That code snippet works on the Mac regardless of whether your application is sandboxed.
In a non-sandboxed Mac app, path will refer to the Documents folder in your home: e.g. /Users/username/Documents.
In a sandboxed app, it refers to a folder within the app sandbox: e.g. /Users/username/Library/Containers/com.yourcompany.YourApp/Documents
See the docs for details.

Answer 2

Apple's Sandboxing guide is very useful, found here.
You basically have a folder dedicated for your app, as described by theAmateurProgrammer in reply to my question here.
~/Library/Container/com.yourcompany.yourappname/
Here is what I have so far, I will improve it later:
//Create App directory if not exists:
NSFileManager* fileManager = [[NSFileManager alloc] init];
NSString* bundleID = [[NSBundle mainBundle] bundleIdentifier];
NSArray* urlPaths = [fileManager URLsForDirectory:NSApplicationSupportDirectory
inDomains:NSUserDomainMask];
NSURL* appDirectory = [[urlPaths objectAtIndex:0] URLByAppendingPathComponent:bundleID isDirectory:YES];
//TODO: handle the error
if (![fileManager fileExistsAtPath:[appDirectory path]]) {
[fileManager createDirectoryAtURL:appDirectory withIntermediateDirectories:NO attributes:nil error:nil];
}

Answer 3

Converting #Mazyod's answer into Swift (5.1):
var appPath: URL? {
//Create App directory if not exists:
let fileManager = FileManager()
let urlPaths = fileManager.urls(for: .applicationSupportDirectory, in: .userDomainMask)
if let bundleID = Bundle.main.bundleIdentifier, let appDirectory = urlPaths.first?.appendingPathComponent(bundleID,isDirectory: true) {
var objCTrue: ObjCBool = true
let path = appDirectory.path
if !fileManager.fileExists(atPath: path,isDirectory: &objCTrue) {
do {
try fileManager.createDirectory(atPath: path, withIntermediateDirectories: true, attributes: nil)
} catch {
return nil
}
}
return appDirectory
}
return nil
}
However, the directory has changed and I am not sure that the additonal repetition of the bundle ID is needed as the path is
"/Users/**user name**/Library/Containers/**bundleID**/Data/Library/Application Support/**bundleID**".
But it seems to work.

Answer 4

Is is even easier. For sandboxed apps on macOS the function NSHomeDirectory gives you the path where you have read and write access and can save all your files. It will be a path like this
/Users/username/Library/Containers/com.yourcompany.YourApp