Source code for SPV node on iOS - where to start? 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?
BreadWallet for iOS is open source, has a permissive license, and uses SPV https://github.com/voisine/breadwallet/blob/78d67870cdb887bab69ffeab8d808a3cb24d3759/BreadWallet/BRPeer.m