Most people don’t know it but you can build our OpenBazaar backend server and use it as a bridge framework on mobile devices (Android and iOS). This allows you to start up your own OpenBazaar full node and you then have access to the full API and can build apps that interact with other desktop or mobile nodes. You can build the binary yourself using our GitHub source code at https://github.com/OpenBazaar/openbazaar-go.
I also have the pre-built iOS framework available https://www.dropbox.com/s/6qnl5oc16dhjvv2/Mobile.framework.zip?dl=0
I’ll try to write more of a tutorial soon. The code looks like this and you just have to create a MobileNewOB() object that takes several parameters and send it a start or stop command from your Objective-C or Swift code.