I have written an installerplugin to show a custom pane in the pkg installer. I want to display the pane only during first install and hide it when upgrading. I know how to find out if the package has already been installed or not but I am not able to figure out the logic of showing/hiding the installerpane based on a runtime decision.
One method I could think of is that the installerplugin contains an Installersection outlet called parentSection. And installersection class has a function shouldload whose return value decides whether the section should be loaded or not. And this article mentions that the installersection methods can be overloaded. But I am unable to think of a way to overload the functions as parentSection is just an object inside the installerpane class.
Even though it's been several months since sanmukh asked this question, I figured I would post the answer since I figured out how to do this.
The solution is indeed to subclass InstallerSection and override the shouldLoad method. To use it, you have to edit your plug-in's Info.plist file and change the entry for "NSPrincipalClass" (or "Principal Class" as it appears in Xcode 4) to be your new InstallerSection derived class. Afterwards when your package loads, the new shouldLoad method will be called, allowing you to programmatically decide whether the installer pane should be visible.