Registering an icon for my application's document type.

Question

I'm trying to register an icon for my app's document type. After reading Declaring New Uniform Type Identifiers and looking at /Developer/Examples/Sketch I came up with something like this in my Info.plist:

<key>CFBundleDocumentTypes</key>
<array>
  <dict>
    <key>CFBundleTypeRole</key>
    <string>Viewer</string>
    <key>LSItemContentTypes</key>
    <array>
      <string>com.mycompany.myextension</string>
    </array>
    <key>NSDocumentClass</key>
    <string>NSString</string>
  </dict>
</array>

...

<key>UTExportedTypeDeclarations</key>
<array>
  <dict>
    <key>UTTypeDescription</key>
    <string>Blah blah blah</string>
    <key>UTTypeConformsTo</key>
    <array>
      <string>public.data</string>
    </array>
    <key>UTTypeIconFile</key>
    <string>My-file-icon.icns</string>
    <key>UTTypeIdentifier</key>
    <string>com.mycompany.myextension</string>
    <key>UTTypeTagSpecification</key>
    <dict>
      <key>public.filename-extension</key>
      <array>
        <string>myextension</string>
      </array>
    </dict>
  </dict>
</array>

Now, everything is fine and dandy, i.e. my program is opened when I click on a file with my extension, etc. However, the document icon is not registered with the OS, i.e. I see an ugly blank icon instead of my beautiful My-file-icon.icns. I suspect that I'm missing something in the plist above, any ideas?

Answer 1

Your UTI declaration in the Info.plist appears to be correct, however I noticed an other issue. If you application is a document-based application you need to replace the NSString in following entry with your NSDocument subclass:

<key>NSDocumentClass</key>
<string>NSString</string>

For example it's "SKTDocument" in Sketch:

<key>NSDocumentClass</key>
<string>SKTDocument</string>

Edit: Please also make sure to use your own reverse domain name for your exported UTIs. This ensures that UTIs are unique. For example its com.mindnode.MindNode.MindNodeDocument in my case.

Answer 2

Try putting the icon name in the CFBundleTypeIconFile key in the the CFBundleDocumentTypes array, not in the UTIExportedTypesDeclaration array.

And of course make sure that My-file-icon.icns is in your target's Copy Bundle Resources build phase and is being copied into Contents/Resources in your app's bundle.