Apple recently changed their policy regarding screenshots for iOS applications in the App Store: you must supply any changes to your screenshots by the time of approval, or the existing screenshots will be locked down until the next time you submit and are approved.

Long story short: you better have those screenshots ready at submission time or very shortly after. And the screenshots had better be something you are willing to live with for a good long while.

This is a dramatic change from the old policy, under which developers could update screenshots at their leisure. This afforded a workflow where a developer might put all of their effort into the actual development of the app, submit it, and then get to work fine-tuning their screenshots for the marketing aspect of selling in the App Store.

One reason for putting off the job of creating screenshots is that creating them is time-consuming and tedious, even with a relatively simple app. For a more complex app, or one that is localized into many languages, the challenge is that much greater.

Last night, at our local Boston CocoaHeads meeting, I learned about a well-timed solution for this problem. Kent Sutherland, the programmer for Flexibits, showed off how he uses an automated screenshot-capture procedure to tame the task of generating Fantastical’s many screenshots, in many languages.

His approach uses a novel technique in which the target app itself is built with customized screen-capturing code compiled right in. Then the app can be driven through the iOS Simulator with WaxSim, a command-line tool for launching the simulator with various options. He was kind enough to share a sample project in which he applies the same technique to Apple’s UICatalog sample app:

Click to download Kent’s UICatalog sample.

After downloading the sample, navigate to the “Screenshots” folder to find the real goodies. The Readme.txt in that folder has simple instructions for kicking off the process. In a nutshell: just open the Screenshots folder in the Terminal, and type “python make_screenshots.py output”. Then watch as the iOS simulator cranks through the process of generating 12 screenshots for UICatalog before you’ve had a chance to wipe that tear of joy from the corner of your eye.

I plan to build more iOS software in the future, and something like this will undoubtedly be a lifesaver when I have significant screenshots to generate. My only existing iOS app, Shush, only has 4 screenshots in one language, and I still found it tedious enough to re-generate screenshots that I hesitated to improve the UI because of the work of another round of, ahem, bitsplitting.

The same approach is also applicable to Mac apps. Currently I go through a similarly tedious procedure of manually navigating and cajoling the app into a specific state before taking a screenshot by hand. This could all be driven by automated capture code built into a custom version of the app, where I could also imagine other niceness such as adding annotations to illustrative screenshots, being added to the process.

If you’re selling apps on the iOS App Store, Apple’s policy change makes it imperative that you come up with a workflow for effortlessly and quickly generating screenshots. Thanks to Kent’s generous sharing of his approach, your work is mostly done for you.