Asset Reference - Check if Contract Account is Opted into Asset

[mangoplane]

Hi,

How do I check whether a contract is opted in, but has 0 of the asset? Right now I can just check to see if the balance is 0, and then proceed to close out. It will work. But it won't have the precision and error handling by checking for this condition before trying to do it.

// check we have opted in the asset, and its balance is 0.
byte[] appAddress = CurrentApplicationAddress;
AccountReference contract = appAddress.ToAccountReference();
ulong assetBalance = contract.AssetBalance(assetReference);

Kind regards.