Update iOS config.

Author: CaiJingLong

example/ios/Podfile

@@ -10,80 +10,29 @@ project 'Runner', {
   'Release' => :release,
 }
 
-def parse_KV_file(file, separator='=')
-  file_abs_path = File.expand_path(file)
-  if !File.exists? file_abs_path
-    return [];
+def flutter_root
+  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
+  unless File.exist?(generated_xcode_build_settings_path)
+    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
   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
-  # 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) && 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
+  File.foreach(generated_xcode_build_settings_path) do |line|
+    matches = line.match(/FLUTTER_ROOT\=(.*)/)
+    return matches[1].strip if matches
   end
+  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
+end
 
-  # Keep pod path relative so it can be checked into Podfile.lock.
-  pod 'Flutter', :path => 'Flutter'
+require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)
 
-  # Plugin Pods
+flutter_ios_podfile_setup
 
-  # 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 => File.join(symlink, 'ios')
-    specPath = "#{path}/ios/#{name}.podspec"
-    pod name,:path=>specPath
-  end
+target 'Runner' do
+  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
 end
 
-# Prevent Cocoapods from embedding a second Flutter framework and causing an error with the new Xcode build system.
-install! 'cocoapods', :disable_input_output_paths => true
-
 post_install do |installer|
   installer.pods_project.targets.each do |target|
-    target.build_configurations.each do |config|
-      config.build_settings['ENABLE_BITCODE'] = 'NO'
-    end
+    flutter_additional_ios_build_settings(target)
   end
 end