Update podfile

Author: bbedward

ios/Podfile

@@ -15,50 +15,67 @@ def parse_KV_file(file, separator='=')
   if !File.exists? file_abs_path
     return [];
   end
-  pods_ary = []
+  generated_key_values = {}
   skip_line_start_symbols = ["#", "/"]
-  File.foreach(file_abs_path) { |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)
-        pods_ary.push({:name => podname, :path => podpath});
-      else
-        puts "Invalid plugin specification: #{line}"
-      end
-  }
-  return pods_ary
+  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!
-  # 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')
+  use_modular_headers!
+  
+  # Flutter Pod
 
-  # Flutter Pods
-  generated_xcode_build_settings = parse_KV_file('./Flutter/Generated.xcconfig')
-  if generated_xcode_build_settings.empty?
-    puts "Generated.xcconfig must exist. If you're running pod install manually, make sure flutter packages get is executed first."
-  end
-  generated_xcode_build_settings.map { |p|
-    if p[:name] == 'FLUTTER_FRAMEWORK_DIR'
-      symlink = File.join('.symlinks', 'flutter')
-      File.symlink(File.dirname(p[:path]), symlink)
-      pod 'Flutter', :path => File.join(symlink, File.basename(p[:path]))
+  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) && 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 => '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.map { |p|
-    symlink = File.join('.symlinks', 'plugins', p[:name])
-    File.symlink(p[:path], symlink)
-    pod p[:name], :path => File.join(symlink, 'ios')
-  }
+  plugin_pods.each do |name, path|
+    symlink = File.join('.symlinks', 'plugins', name)
+    File.symlink(path, symlink)
+    pod name, :path => File.join(symlink, 'ios')
+  end
 end
 
 # Prevent Cocoapods from embedding a second Flutter framework and causing an error with the new Xcode build system.
@@ -70,4 +87,4 @@ post_install do |installer|
       config.build_settings['ENABLE_BITCODE'] = 'NO'
     end
   end
-end
+end