The recent release of xScope 3.0 is our first product to use the new application sandbox that will soon become a requirement for submission to the Mac App Store. I’d like to share some experiences and advice on how to use it in your own products.

First off, Ivan Krstić and the rest of the team at Apple have done a great job in making the whole process easy to implement. Adding entitlements and signing your code will be the least of your worries as you transition to the new sandbox.

Of course there are some applications that have a harder time than others: primarily if those apps require access to all or part of the filesystem (think about syncing data with Transmit, for example.) Apps that make use of AppleScript for inter-app communication will also have a difficult time: this includes our Take Five app. Apple is actively listening to developers who are encountering these types of issues, so if you haven’t filed a Radar yet, quit bitching.

Speaking of Radar, we encountered a fairly nasty problem after launching xScope. Many of our customers are designers and developers who love SSDs. It’s common to use a symlink in your Home folder to put big datasets like Pictures, Music and Movies on a separate hard drive. When you do this, folder access in the application sandbox container breaks. A small number of users who use symlinks are also getting crashes after launching the app that was downloaded from the Mac App Store:

xpchelper reply message validation: sandbox creation failed: 1002
Container object initialization failed: The file couldn’t be opened.

We also encountered a problem when using Sparkle to update an app running in a sandbox: an app can’t update its own binary. Changing Sparkle so that it uses an XPC service is a major architectural change, so we decided to remove the sandbox for the version we distribute on the website.

Besides being the path of least resistance, it also gives us a version of xScope that doesn’t run into the sandbox bugs reported above. I highly recommend that you give yourself this option for any customers that experience sandbox related problems.

All things considered, adding an application sandbox has been a fairly smooth transition. But it’s also clear that we’ve only just begun putting the genie back in the bottle.

Updated January 27th, 2012: The bug reported above is a duplicate of Radar 9865143.