Modernize Podfile in examples/platform_view (#17643)

.gitignore

@@ -66,6 +66,7 @@ unlinked_spec.ds
 **/ios/**/DerivedData/
 **/ios/**/Icon?
 **/ios/**/Pods/
+**/ios/**/.symlinks/
 **/ios/**/profile
 **/ios/**/xcuserdata
 **/ios/.generated/

examples/platform_view/README.md

 # Example of switching between full-screen Flutter and Platform View
 
-This project demonstrates how to bring up a full-screen iOS/Android view from a full-screen Flutter view along with passing data back and forth between the two.
\ No newline at end of file
+This project demonstrates how to bring up a full-screen iOS/Android view from a
+full-screen Flutter view along with passing data back and forth between the two.
+
+On iOS we use a CocoaPods dependency to add a Material Design button, and so
+`pod install` needs to be invoked in the `ios/` folder before `flutter run`:
+
+```
+pushd ios/ ; pod install ; popd
+flutter run
+```

examples/platform_view/ios/Podfile

 # Uncomment this line to define a global platform for your project
 # platform :ios, '9.0'
 
-if ENV['FLUTTER_FRAMEWORK_DIR'] == nil
-  abort('Please set FLUTTER_FRAMEWORK_DIR to the directory containing Flutter.framework')
-end
-
-target 'Runner' do
-  use_frameworks!
-
-  # Pods for Runner
-  pod 'MaterialControls'
-  
-  # Flutter Pods
-  pod 'Flutter', :path => ENV['FLUTTER_FRAMEWORK_DIR']
+# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
+ENV['COCOAPODS_DISABLE_STATS'] = 'true'
 
-  if File.exists? '../.flutter-plugins'
-    flutter_root = File.expand_path('..')
-    File.foreach('../.flutter-plugins') { |line|
-      plugin = line.split(pattern='=')
+def parse_KV_file(file, separator='=')
+  file_abs_path = File.expand_path(file)
+  if !File.exists? file_abs_path
+    return [];
+  end
+  pods_ary = []
+  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
-        name = plugin[0].strip()
+        podname = plugin[0].strip()
         path = plugin[1].strip()
-        resolved_path = File.expand_path("#{path}/ios", flutter_root)
-        pod name, :path => resolved_path
+        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
+end
+
+target 'Runner' do
+  # 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')
+
+  # 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]))
+    end
+  }
+
+  # Plugin Pods
+  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')
+  }
+
+  pod 'MaterialControls'
 end
 
 post_install do |installer|

examples/platform_view/ios/Podfile.lock

@@ -3,13 +3,21 @@ PODS:
   - MaterialControls (1.2.2)
 
 DEPENDENCIES:
-  - Flutter (from `/Users/zarah/flutter/bin/cache/artifacts/engine/ios`)
+  - Flutter (from `.symlinks/flutter/ios`)
   - MaterialControls
 
+SPEC REPOS:
+  https://github.com/cocoapods/specs.git:
+    - MaterialControls
+
+EXTERNAL SOURCES:
+  Flutter:
+    :path: ".symlinks/flutter/ios"
+
 SPEC CHECKSUMS:
-  Flutter: d674e78c937094a75ac71dd77e921e840bea3dbf
+  Flutter: 9d0fac939486c9aba2809b7982dfdbb47a7b0296
   MaterialControls: 1c6b29e78d3a13d8dd6a67ed31b6d26eb5de8f72
 
-PODFILE CHECKSUM: d6aabe8e71e2432dda8b99c2a5dbd2bdd65b3c0c
+PODFILE CHECKSUM: 4a320bf98e7f7e414d7d7f5079edf1b2d6679c9b
 
-COCOAPODS: 1.2.1
+COCOAPODS: 1.5.2