Let’s try to use the builtin [A](https://en.wikipedia.org/wiki/A_search_algorithm) in GameplayKit, and see if it works for our current demands.

Prereq work for implementing path finding: eight direction navigation. A tile can find its neighbours within its layer exit(direction:). Currently only within a single map region, because we haven’t implemented interregion links yet.

Spent at huge part of the hour today troubleshooting why my API change to an init method was not being seen by the playground. Weird caching bugs? No; it turns out that XCode was building for target instead of simulator, so the playground didn’t get a rebuilt version of the framework when I hit build. Still don’t know why that changed since last time, but oh well.

Yesterday was a fail for this project, but I did spend the afternoon writing python code as an assignment in the LISA tutorial about Software Defined Networking, so maybe that counts as something? No? Sorry.

The first lesson turns out to be about access control: nothing is public by default, even classes or their init methods. With public access to our classes the playground plays.