TLDR cache can be queried (read only) offline, you cannot save (write) to cache offline.
Caching in the Swift SDK is intended for accessing saved data that has already been saved to the server that has been cached locally. This is why querying using find and first works (data was already saved/cached). You mentioned you have no network, connection, this means you can’t save to a Parse Server (your error) and you cannot update the cache (because only successful server responses are cached). You can learn more about cached responses via Apple’s documentation.
The Swift SDK doesn’t have any local storage outside of the aforementioned cache and .current Objects in the Keychain.
It seems you are looking for something like saveEventually in the other SDKs. The Swift SDK doesn’t have this because it doesn’t have local storage. To mimic saveEventualy behavior, you will need to manually save your data using your own local storage when there’s no network connection and then push that data to your server when the connection is available.
Technically the Swift SDK doesn’t need any other local storage as developers can encode/save their own objects to their local storage mediums easily. Even if someone wanted to add saveEventually or something with local storage, it should be protocol based:
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