Cannot install pg gem in Mavericks with Postgres.app

Question

I am trying to install the pg gem for use with Postgres.app on my local machine. I am running Mavericks.

Postgres.app is installed and running fine, but I cannot get

Answer 1

In my case (running Postgres.app v9.3.4.2) it only seemed to work when prepending the environment architecture flags:

env ARCHFLAGS="-arch x86_64" gem install pg -- \
--with-pg-config=/Applications/Postgres.app/Contents/Versions/9.3/bin/pg_config