In my cocoa apps i'm often saving some user or application data, e.g. in
NSString *folder = @"~/Library/Application Support/MyAppName/appData.xyz";
But for testing you need to modify or delete that files. And I'm always start from beginning, where to find that file in debug-mode. Because it is not saved to the real path. XCode save the files in a Container named like the bundle identifier.
Usually /Users/Me/Library is hidden in Finder. You can use Terminal to show all hidden file and folder.