How to create a directory in downloads folder with Swift on macOS? Permission exception

Question

I am struggling to simply create a folder in the users download directory on macOS with this code:

static func createFolderInDownloadsDirectory() {
    let downloadsDirectory = FileManager.default.urls(for: .downloadsDirectory, in: .userDomainMask).first!
    let downloadsDirectoryWithFolder = downloadsDirectory.appendingPathComponent("FolderToCreate")
    
    do {
        try FileManager.default.createDirectory(at: downloadsDirectoryWithFolder, withIntermediateDirectories: true, attributes: nil)
    } catch let error as NSError {
        print(error.localizedDescription)
    }
}

This is the output:

You don’t have permission to save the file “FolderToCreate” in the folder “Downloads”. 

How can I fix this?

Answer 1

Xcode 9 and later enables sandboxing by default, which severely limits interactions with the system. However you can still write to the Downloads folder by adding an entitlement to your app:

Select your target, then Capabilities and set Downloads Folder to Read/Write:

If you have no intention of distributing your app through the Mac App Store, you can turn off sandboxing. Your application can still be signed but users will get a warning when they first launch your app.