title: How to add .a libraries on flutter plugin via podspec
body: <p>I am trying to include <code>.a</code> files on the iOS side of the plugin. Below is my file structure.
  <a href="https://i.stack.imgur.com/Yl5eS.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Yl5eS.png" alt="enter image description here"></a></p>
  
  <p>Now when I try to add .a files via <code>vendored_libraries</code> on <code>podspec</code>, pod install is successfully completed. And when I compile the code, I get <code>Library Not Found  -lAccuraFace</code></p>
  
  <p>I tried to add the .a file on the Link Binary With Libraries section on the build phase on the Pod target. It's still the same, how can I define the podspec in such a way that the .a file is included and linked automatically.</p>
  
  <p>Here is my podspec file for the plugin</p>
  
  <pre><code>Pod::Spec.new do |s|
    s.name             = 'accuraemirates'
    s.version          = '0.0.1'
    s.summary          = 'A new Flutter plugin.'
    s.description      = &lt;&lt;-DESC
  A new Flutter plugin.
                         DESC
    s.homepage         = 'http://example.com'
    s.license          = { :file =&gt; '../LICENSE' }
    s.author           = { 'Your Company' =&gt; 'email@example.com' }
    s.source           = { :path =&gt; '.' }
    s.source_files = 'Classes/**/*'
    s.dependency 'Flutter'
    s.public_header_files = 'Classes/*{.h}'
    s.private_header_files = 'Classes/CodeScan/**/*{.h,.cpp,.a}'
    s.platform = :ios, '8.0'
    s.preserve_paths = 'opencv2.framework'
    s.xcconfig = { 
      'OTHER_LDFLAGS' =&gt; '-framework opencv2 -lAccuraFace',
    }
    s.ios.vendored_frameworks = 'opencv2.framework', "CoreVideo.framework", "Foundation.framework", "CoreGrpahics.framework", 
    "Accelerate.framework", "CoreMedia.framework", "CoreImage.framework", "QuartzCore.framework", "AudioToolbox.framework", "CoreData.framework", "SystemConfiguration.framework"
    s.ios.vendored_libraries = 'Classes/Framework/*{.a}', "libz.1.dylib", "c++", "stdc++"
  
    # Flutter.framework does not contain a i386 slice. Only x86_64 simulators are supported.
    s.pod_target_xcconfig = { 'DEFINES_MODULE' =&gt; 'YES', 'VALID_ARCHS[sdk=iphonesimulator*]' =&gt; 'x86_64' }
    s.swift_version = '5.0'
  end
  </code></pre>
  
  <p>Here is the root podfile</p>
  
  <pre><code>ENV['COCOAPODS_DISABLE_STATS'] = 'true'
  
  project 'Runner', {
    'Debug' =&gt; :debug,
    'Profile' =&gt; :release,
    'Release' =&gt; :release,
  }
  
  def parse_KV_file(file, separator='=')
    file_abs_path = File.expand_path(file)
    if !File.exists? file_abs_path
      return [];
    end
    generated_key_values = {}
    skip_line_start_symbols = ["#", "/"]
    File.foreach(file_abs_path) do |line|
      next if skip_line_start_symbols.any? { |symbol| line =~ /^\s*#{symbol}/ }
      plugin = line.split(pattern=separator)
      if plugin.length == 2
        podname = plugin[0].strip()
        path = plugin[1].strip()
        podpath = File.expand_path("#{path}", file_abs_path)
        generated_key_values[podname] = podpath
      else
        puts "Invalid plugin specification: #{line}"
      end
    end
    generated_key_values
  end
  
  target 'Runner' do
    use_frameworks!
    use_modular_headers!
  
    # Flutter Pod
  
    copied_flutter_dir = File.join(__dir__, 'Flutter')
    copied_framework_path = File.join(copied_flutter_dir, 'Flutter.framework')
    copied_podspec_path = File.join(copied_flutter_dir, 'Flutter.podspec')
    unless File.exist?(copied_framework_path) &amp;&amp; File.exist?(copied_podspec_path)
      # Copy Flutter.framework and Flutter.podspec to Flutter/ to have something to link against if the xcode backend script has not run yet.
      # That script will copy the correct debug/profile/release version of the framework based on the currently selected Xcode configuration.
      # CocoaPods will not embed the framework on pod install (before any build phases can generate) if the dylib does not exist.
  
      generated_xcode_build_settings_path = File.join(copied_flutter_dir, 'Generated.xcconfig')
      unless File.exist?(generated_xcode_build_settings_path)
        raise "Generated.xcconfig must exist. If you're running pod install manually, make sure flutter pub get is executed first"
      end
      generated_xcode_build_settings = parse_KV_file(generated_xcode_build_settings_path)
      cached_framework_dir = generated_xcode_build_settings['FLUTTER_FRAMEWORK_DIR'];
  
      unless File.exist?(copied_framework_path)
        FileUtils.cp_r(File.join(cached_framework_dir, 'Flutter.framework'), copied_flutter_dir)
      end
      unless File.exist?(copied_podspec_path)
        FileUtils.cp(File.join(cached_framework_dir, 'Flutter.podspec'), copied_flutter_dir)
      end
    end
  
    # Keep pod path relative so it can be checked into Podfile.lock.
    pod 'Flutter', :path =&gt; 'Flutter'
  
    # Plugin Pods
  
    # Prepare symlinks folder. We use symlinks to avoid having Podfile.lock
    # referring to absolute paths on developers' machines.
    system('rm -rf .symlinks')
    system('mkdir -p .symlinks/plugins')
    plugin_pods = parse_KV_file('../.flutter-plugins')
    plugin_pods.each do |name, path|
      symlink = File.join('.symlinks', 'plugins', name)
      File.symlink(path, symlink)
      pod name, :path =&gt; File.join(symlink, 'ios')
    end
  end
  
  post_install do |installer|
    installer.pods_project.targets.each do |target|
      target.build_configurations.each do |config|
        config.build_settings['ENABLE_BITCODE'] = 'NO'
      end
    end
  end
  </code></pre>
  
  <p>Is it not possible to add/link <code>.a</code> libraries from <code>podspec</code> file on a flutter plugin.</p>