Transaction hash for signed transaction

I use the following code to get Coinbase Wallet to sign a transaction. When this succeeds Coinbase Wallet opens up our application, but I don’t know how to access the resulting transaction hash.

Where can I find this in the result?

    cbwallet.makeRequest(.init(actions: [Action(jsonRpc: .eth_signTransaction(fromAddress: model.from,
                                                                              weiValue: "0",
                                                                              nonce: nil,
                                                                              gasPriceInWei: model.gas,
                                                                              maxFeePerGas: nil,
                                                                              maxPriorityFeePerGas: nil,
                                                                              gasLimit: nil,
                                                                              chainId: chain.toBlockchain().reference))],
                               account: account)) { [weak self] result in
        switch result {
        case .success(let result):
            switch result.content.first {
            case .success(let string):
            // how do I access the transaction hash?
            case .failure(let actionError):