Error building flutter iOS project using a plugin with static library

Currently I'm trying to use this plugin flutter-zsdk as a dependency of my project and I'm not able to build/run the project for iOS. For Android the project builds/run just fine, but for iOS I get the following error:

Running Xcode build
Xcode build done.                                            3.0s
Failed to build iOS app
Error output from Xcode build:
↳
    2020-02-07 12:20:44.583 xcodebuild[29722:10555466]  DTDeviceKit: deviceType from 00008006-001C498E2206002E was NULL
    2020-02-07 12:20:44.584 xcodebuild[29722:10555578]  DTDeviceKit: deviceType from 00008006-001C498E2206002E was NULL
    2020-02-07 12:20:44.677 xcodebuild[29722:10555344] [MT] DTDeviceKit: deviceType from 00008006-001C498E2206002E was NULL
    2020-02-07 12:20:44.681 xcodebuild[29722:10555344] [MT] DTDeviceKit: deviceType from 00008006-001C498E2206002E was NULL
    2020-02-07 12:20:44.685 xcodebuild[29722:10555344] [MT] DTDeviceKit: deviceType from 00008006-001C498E2206002E was NULL
    ** BUILD FAILED **



Xcode's output:
↳
    Undefined symbols for architecture arm64:
      "_OBJC_CLASS_$_SGD", referenced from:
          objc-class-ref in FlutterZsdkPlugin.o
      "_OBJC_CLASS_$_MfiBtPrinterConnection", referenced from:
          objc-class-ref in FlutterZsdkPlugin.o
    ld: symbol(s) not found for architecture arm64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    note: Using new build system
    note: Planning build
    note: Constructing build description

Could not build the precompiled application for the device.

Error launching application on iDevice.

Note 1: This plugin uses a static library zsdk.a for communication with printers.

Note 2: I opened the flutter-zsdk plugin as a project in Android Studio and I were able to build/run the example_app for both Android and iOS without any extra action… just opened the project, and build and everything worked fine.

So my question: Is there something different in building a project which uses a plugin which in turn uses a static library.a? Do I have to set something in my iOS project configurations in order to be able to build/run properly this kind of plugin dependency?