Travis-CI for Linux

.travis.yml

@@ -1,4 +1,19 @@
-language: objective-c
-osx_image: xcode9
+matrix:
+  include:
+    - os: linux
+      dist: trusty
+      sudo: required
+      language: ruby
+	  before_install:
+	    - export SWIFT_ARCHIVE_URL="https://swift.org/builds/swift-4.0-release/ubuntu1404/swift-4.0-RELEASE/swift-4.0-RELEASE-ubuntu14.04.tar.gz"
+	    - curl ${SWIFT_ARCHIVE_URL} -o ../swift.tar.gz
+		- mkdir ../swift
+		- tar xzf ../swift.tar.gz -C ../swift --strip-components 1
+		- export PATH="$(realpath \"$(pwd)/../swift/usr/bin\"):${PATH}"
+	- os: osx
+      osx_image: xcode9
+      sudo: required
+      language: objective-c
+	   
 script:
- - ./build-install.rb --debug
+  - ./build-install.rb --debug