Fix some issues reported by flutter pub publish

Author: patrick-fu

.gitignore

@@ -1,20 +1,29 @@
-# pub
-.dart_tool/
-.packages
-build/
-pubspec.lock
-
-# api doc
-doc/api/
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
 
-# IntelliJ
+# IntelliJ related
 *.iml
 *.ipr
 *.iws
 .idea/
 
-# mac
-.DS_Store
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
 
-# FVM Version Cache
-.fvm/
+# Flutter/Dart/Pub related
+# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
+pubspec.lock
+**/doc/api/
+.dart_tool/
+build/

analysis_options.yaml

@@ -0,0 +1,4 @@
+include: package:flutter_lints/flutter.yaml
+
+# Additional information about this file can be found at
+# https://dart.dev/guides/language/analysis-options

example/.gitignore

@@ -8,6 +8,7 @@
 .buildlog/
 .history
 .svn/
+migrate_working_dir/
 
 # IntelliJ related
 *.iml
@@ -26,19 +27,17 @@
 .dart_tool/
 .flutter-plugins
 .flutter-plugins-dependencies
-.packages
 .pub-cache/
 .pub/
 /build/
 
-# Web related
-lib/generated_plugin_registrant.dart
-
 # Symbolication related
 app.*.symbols
 
 # Obfuscation related
 app.*.map.json
 
-# Exceptions to above rules.
-!/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release

example/ios/.gitignore

@@ -1,3 +1,4 @@
+**/dgph
 *.mode1v3
 *.mode2v3
 *.moved-aside
@@ -18,6 +19,7 @@ Flutter/App.framework
 Flutter/Flutter.framework
 Flutter/Flutter.podspec
 Flutter/Generated.xcconfig
+Flutter/ephemeral/
 Flutter/app.flx
 Flutter/app.zip
 Flutter/flutter_assets/

ios/.gitignore

@@ -34,4 +34,5 @@ Icon?
 .tags*
 
 /Flutter/Generated.xcconfig
-/Flutter/flutter_export_environment.sh
+/Flutter/ephemeral/
+/Flutter/flutter_export_environment.sh

pubspec.yaml

@@ -4,8 +4,8 @@ version: 1.1.1
 homepage: https://github.com/patrick-fu/flutter_shared_preference_app_group
 
 environment:
-  sdk: '>=2.12.0 <3.0.0'
-  flutter: ">=1.20.0"
+  sdk: '>=2.12.0 <4.0.0'
+  flutter: '>=1.20.0'
 
 dependencies:
   flutter: