feat(share_extension): integrate share_handler package and implement share functionality with updated permissions and entitlements

ios/Podfile

@@ -1,9 +1,12 @@
 # Uncomment this line to define a global platform for your project
-# platform :ios, '13.0'
+platform :ios, '13.0'
 
 # CocoaPods analytics sends network stats synchronously affecting flutter build latency.
 ENV['COCOAPODS_DISABLE_STATS'] = 'true'
 
+# Work around Xcode cycle false-positives by letting CocoaPods not declare IO paths
+install! 'cocoapods', :disable_input_output_paths => true
+
 project 'Runner', {
   'Debug' => :debug,
   'Profile' => :release,
@@ -28,9 +31,19 @@ require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelpe
 flutter_ios_podfile_setup
 
 target 'Runner' do
-  use_frameworks!
+  # Prefer static frameworks to avoid Xcode embed-cycles with app extensions
+  use_frameworks! :linkage => :static
+  use_modular_headers!
 
   flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
+
+  # share_handler addition start
+  target 'ShareExtension' do
+    inherit! :search_paths
+    # Only models are needed in extension to avoid app-only APIs
+    pod "share_handler_ios_models", :path => ".symlinks/plugins/share_handler_ios/ios/Models"
+  end
+  # share_handler addition end
   target 'RunnerTests' do
     inherit! :search_paths
   end
@@ -40,4 +53,15 @@ post_install do |installer|
   installer.pods_project.targets.each do |target|
     flutter_additional_ios_build_settings(target)
   end
+
+  # Reduce chances of embed/cycle: don't embed Swift stdlib explicitly
+  installer.aggregate_targets.each do |aggregate_target|
+    aggregate_target.user_project.native_targets.each do |native_target|
+      if ['Runner', 'ShareExtension'].include?(native_target.name)
+        native_target.build_configurations.each do |config|
+          config.build_settings['ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES'] = 'NO'
+        end
+      end
+    end
+  end
 end