Does this lib support segwit multisig signing ?

[newyangyang]

I want to spend coin of a segwit multisig(2-of-3) address. I already created a tx, signed it with the first private key. How can I use this library to make the second signing? I can provide: 1. the hex result after the first signing, 2. the prevtxs of this transaction, 3. the second private key. With all three of them, a bitcoin node can sign the transaction correctly, using signrawtransaction method. I tried to follow this example, with testMultisignatureScripts method. But got a bad decoded tx on BTCTransaction alloc initWithData:BTCDataFromHex. I wonder what should I do with this library ?