See these 1.1.x to 1.2.0 upgrade instructions to bring your existing apps up to speed.

• Enhancements
  • [CodeReloader] The lib/ directory is now code reloaded by default along with web/ in development
  • [Channel] Add subscribe/2 and unsubscribe/2 to handle external topic subscriptions for a socket
  • [View] Generate private render_template/2 clauses for views to allow overriding render/2 clauses before rendering templates
  • [Channel] Add :phoenix_channel_join instrumentation hook
• JavaScript client enhancements
  • Add Presence object for syncing presence state between client and server
• Deprecations
  • [Endpoint] Generated subscribe/3 and unsubscribe/2 clauses have been deprecated in favor of subscribe/2 and unsubscribe/1 which uses the caller's pid
  • [PubSub] Phoenix.PubSub.subscribe/3 and Phoenix.PubSub.unsubscribe/2 have been deprecated in favor of subscribe/2 and unsubscribe/1 which uses the caller's pid