```ruby
cask :v1 => 'omnifocus' do
  version :latest
  sha256 :no_check

  url 'http://www.omnigroup.com/download/latest/omnifocus'
  homepage 'http://www.omnigroup.com/products/omnifocus/'
  license :commercial

  app 'OmniFocus.app'

  zap :delete => [
                  '~/Library/Application Support/OmniFocus/Plug-Ins',
                  '~/Library/Application Support/OmniFocus/Themes',
                  '~/Library/Preferences/com.omnigroup.OmniFocus.plist',
                 ]
end
```

Update OmniFocus to use versioned downloads
user
```ruby
cask :v1 => 'omnifocus' do
  if MacOS.release <= :mountain_lion
    version '1.10.6'
    sha256 'bd3aa44dced86fc3921c01f4467422a7b87a92afbd4be642ea4d4bb8b14b728c'
    url "http://www.omnigroup.com/ftp1/pub/software/MacOSX/10.6/OmniFocus-#{version}.dmg"

    zap :delete => [
                    '~/Library/Application Support/OmniFocus/Plug-Ins',
                    '~/Library/Application Support/OmniFocus/Themes',
                    '~/Library/Preferences/com.omnigroup.OmniFocus.plist'
                   ]
  else
    version '2.0.4'
    sha256 'c5667f950147cbc33387ab45267b15666eef558391aeaf8d6df543a65edaa799'
    url "http://www.omnigroup.com/ftp1/pub/software/MacOSX/10.9/OmniFocus-#{version}.dmg"

    zap :delete => [
                    '~/Library/containers/com.omnigroup.omnifocus2',
                    '~/Library/Preferences/com.omnigroup.OmniFocus2.LSSharedFileList.plist',
                    '~/Library/Preferences/com.omnigroup.OmniSoftwareUpdate.plist',
                    '~/Library/Caches/Metadata/com.omnigroup.OmniFocus2'
                   ]
  end

  name 'OmniFocus'
  homepage 'https://www.omnigroup.com/omnifocus/'
  license :commercial

  app 'OmniFocus.app'
end
```
assistant