iOS native extension - cannot package app

I am trying to integrate the MixPanel SDK as a native extension to our project. I can compile the .ANE fine, but when I try to package my application I get the following error:

Undefined symbols for architecture armv7: utf8_nextCharSafeBody, referenced from:_validate_dispatch_data_partial_string from libPods-MixPanel.a(MPVWebSocket.o)

the library is open source, heres this file:

mixpanel-iphone/MPWebSocket.m at master · mixpanel/mixpanel-iphone · GitHub

The definition of this function comes from this import:

#import <unicode/utf8.h>

which comes from usr/incude -> unicode -> utf8.h according to XCode. 

How can I include this file? Do I need to include it at all?

My platform.xml looks like this:

<platform xmlns="http://ns.adobe.com/air/extension/15.0">

   <sdkVersion>6.0</sdkVersion>

   <linkerOptions>

   <option>-ios_version_min 6.0</option>

   <option>-framework Accelerate</option>

   <option>-framework CoreTelephony</option>

   <option>-framework Security</option>

   </linkerOptions>

</platform>