I have developed a mac application without using sandbox.
now i want to send it to the mac appSore, i buy my certificate, all is good.
I read this: Apple doc and in xcode i set the user selected file,music folder... to read/write access.
My application let the user chose from a folder any type of file, do some treatment and let the user chose where to save the new file.
To chose files, user can open folder with NSOpenPanel or with the open with functionality or drag-and-drop files.
Also the application can delete files.
I dont know if there's other things to do to sandbox the application (or a tool to test if it is sandboxed) I come from ios this is why i'm asking :)
You can look in the Console when the application is running to view if sandboxd or pboxd logs messages referring to your application.
The format is: sandboxd[53037] ([53035]): AppName(53035)
I don't know if there are other processes who may log sandbox violation, but you can see them, if they are referring to your application.