libxml2 header not found using pods

Today I learned something new! Of course, learned it after a frustrating pounding my head day at work, but still learned something new, and I sort of understand how CocoaPods work!

I’m working in an iOS mobile application where Project A has a dependency on Project B, or in more English terms, Project A uses Project B. Dependencies in iOS applications are known as CocoaPods. Project B uses a library called libxml2, which is an XML C parser.

In order to apply this dependency, one must pod install using the Podfile. After the pod install, Project B now includes Project A (with the libxml2 library).

However! I receive this awful build error: "Lexical or Preprocessor Issue 'libxml2/tree.h' file not found"

Upon inspection, the tree.h does exist and it’s in the right location. So what could be wrong? If you google this error, you will receive the same instructions on how everyone (except me) has resolved this issue.

Set HEADER SEARCH PATHS to $(SDKROOT)/usr/include/libxml2 and other linker flag stuff, but we did do that in Project A & THAT DOESN’T WORK! Project B is having the not found issue!

The solution is:

Make sure you set spec.libraries to the xml2 library and spec.xconfig to the Header Search Pathslike in the Pod’s (in this case, Project A) .podspec file so:

Pod::Spec.new do |spec|
  spec.libraries = ['xml2.2']
  spec.xconfig = { 'HEADER_SEARCH_PATHS' => '$(SDKROOT)/usr/include/libxml2' }

A Podspec file gives detailed information about the Pods being used in the Podfile. Setting the spec.libraries and spec.xconfig to the correct library and Header Search Paths allows the Project B to be able to find the correct header that is used in it’s pod, Project A. Only setting Project B’ project’s HEADER SEARCH PATHS only includes the headers used in its project, and not the pods.

Hope if you bump into this problem, you’ll know exactly what to do now :)