See #18. Add Gitter Travis CI webhook notifications

.travis.yml

@@ -1,6 +1,12 @@
 language: objective-c
 
 notifications:
+  webhooks:
+    urls:
+      - https://webhooks.gitter.im/e/a7cbe520877895f3154a
+    on_success: change  # options: [always|never|change] default: always
+    on_failure: always  # options: [always|never|change] default: always
+    on_start: true     # default: false
   email:
     on_success: never
     on_failure: change