I'm working on a proof-of-concept for a blockchain project and at its core it will need a modified SPV node running on iOS. The reason I need to modify it is so I can build non-standard (e.g. OP_RETURN) scripts without seat-of-the-pants techniques like hacking into the transaction hex.
I'm aware of some basic starting points such as picocoin and libbitcoin which I should be able to compile for iOS. But is there anything else available that would specifically make an SPV node easier to develop on iOS?