Basic CloudKit authentication plugin. v1 is Capacitor 4, v2 is Capacitor 5, v3 is Capacitor 6.

npm install capacitor-cloudkit
npx cap sync

Each different platform requires a different ckAPIToken.

• Web: Token configured for postMessage.
• iOS: Token configured to redirect to your container's URL scheme. It'll show up on the CloudKit dashboard in a dropdown when you create an API key. Mine is cloudkit-icloud.baseline.getbaseline.app://, so I'll be using that as an example. I set mine to cloudkit-icloud.baseline.getbaseline.app://callback.
• Android: Token configured to redirect to https://example.com or some similar existant but blank domain.

• Add your callback URL as a URL scheme in your app, in the Info tab. (e.g. cloudkit-icloud.baseline.getbaseline.app)
• Add the following to the beginning of func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey: Any] = [:]) -> Bool in AppDelegate:

if (url.scheme == "PUT CALLBACK URL SCHEME HERE (e.g. cloudkit-icloud.baseline.getbaseline.app)") {
    NotificationCenter.default.post(name: NSNotification.Name("cloudkitLogin"), object: url);
}

• authenticate(...)
• fetchRecord(...)
• Interfaces

authenticate(options: SignInOptions) => Promise<{ ckWebAuthToken: string; }>

Returns: Promise<{ ckWebAuthToken: string; }>

fetchRecord(options: FetchRecordOptions) => Promise<any>

Only available on iOS.

Returns: Promise<any>