I am trying to use iCloud with SwiftUI. I just want to be able to read/write json files stored there. I believe I have taken all the proper steps to get there, including the necessary changes to Signings & Capabilities and the addition of settings in info.plist. I have set up iCloud on the simulator. But the following code always returns nil for the URL:

 let driveURL = FileManager.default .url(forUbiquityContainerIdentifier:  
        nil)?.appendingPathComponent("Documents")
                if driveURL != nil {
                        print("iCloud available")
                        let fileURL = driveURL!.appendingPathComponent("test.txt")
                        try? "Hello word".data(using: .utf8)?.write(to: fileURL)
                    } else {
                        print("iCloud not available")
                    }

What am I missing?