RubyMotionでUndefined symbols for architecture i386:エラーが出たら

※コメントで`rake clean:all`の方が良いと教えてもらいました。(2014/05/22追記)

```
rake clean:all
```

----
----

一度`build`ディレクトリを消してrakeし直す。

* バージョン

```
motion --version
----------
2.27
----------
```

* エラー

```
rake
----------
  WARNING! BubbleWrap::HTTP is deprecated and will be removed, see https://github.com/rubymotion/BubbleWrap/issues/308
  WARNING! Switch to a different networking library soon - consider AFNetworking: http://afnetworking.com/
  WARNING! You can use the 'bubble-wrap-http' gem if you need compatibility: https://github.com/rubymotion/BubbleWrap-HTTP
     Build ./build/iPhoneSimulator-7.1-Development
      Link ./build/iPhoneSimulator-7.1-Development/KeyValueFun.app/KeyValueFun
Undefined symbols for architecture i386:
  "_rb_objc_autorelease", referenced from:
      _vm_ivar_set in response.rb.o
      _vm_ivar_set in http.rb.o
      _vm_ivar_set in query.rb.o
      _vm_ivar_set in user.rb.o
  "_rb_objc_type", referenced from:
      _vm_rval_to_char in response.rb.o
      _vm_rval_to_uchar in response.rb.o
      _vm_rhash_store in response.rb.o
      _vm_rval_to_char in http.rb.o
      _vm_rval_to_uchar in http.rb.o
      _vm_rhash_store in http.rb.o
      _vm_rval_to_char in query.rb.o
      ...
     (maybe you meant: _rb_objc_type_size)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
rake aborted!
Command failed with status (1): [/Applications/Xcode.app/Contents/Developer...]
/Library/RubyMotion/lib/motion/project/builder.rb:306:in `build'
/Library/RubyMotion/lib/motion/project/app.rb:78:in `build'
/Library/RubyMotion/lib/motion/project/template/ios.rb:68:in `block (2 levels) in <top (required)>'
/Library/RubyMotion/lib/motion/project/template/ios.rb:122:in `block in <top (required)>'
Tasks: TOP => build:simulator
(See full trace by running task with --trace)
----------
```

* buildディレクトリを消す

```
rm -r build
```

* 正常完了

```
rake
----------
  WARNING! BubbleWrap::HTTP is deprecated and will be removed, see https://github.com/rubymotion/BubbleWrap/issues/308
  WARNING! Switch to a different networking library soon - consider AFNetworking: http://afnetworking.com/
  WARNING! You can use the 'bubble-wrap-http' gem if you need compatibility: https://github.com/rubymotion/BubbleWrap-HTTP
     Build ./build/iPhoneSimulator-7.1-Development
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-http-1.6.0/motion/http/response.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/shortcut.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/util/deprecated.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/lib/bubble-wrap/version.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/ios/app.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/util/constants.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/ui_alert_view.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/ns_notification_center.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/ios/device.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/ns_user_defaults.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/app.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/device/screen.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/kvo.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/device.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/json.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/ns_index_path.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/ns_url_request.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/pollute.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/persistence.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/string.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/time.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/device/ios/camera_wrapper.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/device/ios/camera.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/core/device/ios/screen.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/ui_view_controller_wrapper.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/ui_control_wrapper.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/ui_view_wrapper.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/ui_bar_button_item.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/pollute.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/network-indicator/network-indicator.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-1.6.0/motion/ui/ui_activity_view_controller_wrapper.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-http-1.6.0/motion/http.rb
   Compile /Users/shu/.rbenv/versions/2.1.1/lib/ruby/gems/2.1.0/gems/bubble-wrap-http-1.6.0/motion/http/query.rb
   Compile ./app/app_delegate.rb
   Compile ./app/user.rb
    Create ./build/iPhoneSimulator-7.1-Development/KeyValueFun.app
      Link ./build/iPhoneSimulator-7.1-Development/KeyValueFun.app/KeyValueFun
    Create ./build/iPhoneSimulator-7.1-Development/KeyValueFun.app/PkgInfo
    Create ./build/iPhoneSimulator-7.1-Development/KeyValueFun.app/Info.plist
      Copy ./resources/Default-568h@2x.png
    Create ./build/iPhoneSimulator-7.1-Development/KeyValueFun.dSYM
  Simulate ./build/iPhoneSimulator-7.1-Development/KeyValueFun.app
2014-05-21 21:28:04.438 KeyValueFun[28707:90b] Application windows are expected to have a root view controller at the end of application launch
(main)> 
----------
```