restore state AUV3 extension

Hello


I'm implementing an AUV3 extension (AUAudioUnit) and I would like to know how to restore the state of the instance when the extension is loaded from the host. The extension should save/restore several float parameters each time the extension quits/opens. The documentation mentions the "fullState" poperty but it's not clear if/when that propery is set by the host.


Also I would like to save a file specific to the running instance. So if 2 instances of the extension are running by the host, there would be two different files saved. Are there several specific directories related to each instance ?


Thanks