Update readme with build instructins

README.md

@@ -1,5 +1,7 @@
 # CunixODBC
 
+Intended for demonstation purposes only.
+
 Swift module maps for [unixODBC](https://github.com/lurcher/unixODBC), which allow you to use the unixODBC C library in your Swift project.
 
 Note - from Swift 4.2 you can pull the unixODBC library directly into your Swift project and will not need to use this repository (you can see an example of this in [Swift-Kuery-PostgreSQL](https://github.com/IBM-Swift/Swift-Kuery-PostgreSQL/tree/master/Sources/CLibpq)).
@@ -26,6 +28,32 @@ Add `CunixODBC` to your target's dependencies:
 import CunixODBC
 ```
 
+#### Build and test linking
+
+You must have unixODBC installed on your machine:
+
+- MacOS:
+```
+brew install unixodbc
+```
+- Linux:
+```
+apt-get install unixodbc-dev
+```
+Since brew doesn't install the files to the expected place you must provide a linker to swift for any project that depends on this:
+
+```
+swift build -Xcc -I/usr/local/Cellar/unixodbc/2.3.7/include
+swift run -Xcc -I/usr/local/Cellar/unixodbc/2.3.7/include
+swift test -Xcc -I/usr/local/Cellar/unixodbc/2.3.7/include
+```
+
+#### Using with Xcode:
+
+You must add the xcconfig file from this repo to your project. Then generate the project using:
+```
+swift package generate-xcodeproj --xcconfig-overrides unixodbc.xcconfig
+```
 ## Community
 
 We love to talk server-side Swift, and Kitura. Join our [Slack](http://swift-at-ibm-slack.mybluemix.net/) to meet the team!

unixodbc.xcconfig

@@ -0,0 +1,2 @@
+HEADER_SEARCH_PATHS = /usr/local/Cellar/unixodbc/2.3.7/include
+LIBRARY_SEARCH_PATHS = /usr/local/Cellar/unixodbc/2.3.7/lib