What is the use of "Identifier" and "Signature" in the "Info.plist

This must be another basic question, but I couldn’t find the answer on the forum after reasonable effort, so…

What is the use of “Identifier” and “Signature” under the “Info.plist Entries → Simple View → Basic Information” in the “Edit Active Target” menu in Xcode? My understanding is for the former it’s something like “com.companyname.appname” and the latter is a 4-letter code that must be applied somewhere. If it’s true, where should I apply for this ‘signature’? (to avoid duplicate, obviously)


It looks like this is the place to check/register creator codes: http://developer.apple.com/dev/cftype/

– Rob

Cool - so the creator code is for identifying a file’s owner application, and ‘identifier’ is for storing user preferences? Any other use of these two thingies?

I won’t claim to be an expert on the topic but…

The creator code can be used for a couple of things. First, it allows you to, in essence, map files to an application. For instance, if your app creates documents, the documents could be assigned the app’s creator code so that they would open in your app when the Finder is used to open them. The second reason that a creator code is useful is that it allows scripts to easily find the application file using a single line of code.

tell application “Finder” to set appPath to application file id “ToyS” as text

The same can be done with the CFBundleIdentifier.

tell application “Finder” to set appPath to application file id “com.apple.ScriptEditor” as Unicode text

That’s about the extent of my knowledge on the topic. I imagine that you can poke around at ADC and find more detailed and accurate info.

– Rob

Much appreciated Rob!