Donald Hays

Maidenhead Converter 2.2.0/2.2.1 and the Importance of QA

August 29, 2015

Maidenhead Converter 2.2.0 went live about a week ago, and—due to a bug—2.2.1 followed soon after.

There are two features in these releases, and several bug fixes. I added the ability to pick a format for distances, allowing you to choose between Metric and Imperial. This is presently only used for the accuracy label when tracking your location, but it’ll also be used for other features I want to add later.

I also improved VoiceOver accessibility support throughout the app. You can navigate menus and work the keypads via VoiceOver. I don’t know if I really have any audience for VoiceOver, but it’s a good thing to do and I wanted to practice implementing it anyway.

2.2.0 also fixed a few very minor display issues. A few views weren’t aligned well on all devices, and text could clip on some others. Also, iOS 9 will change the system font from Helvetica Neue to San Francisco. When displaying text in iOS, you can ask the OS to give you the “system font” of a specific weight and size, but there were a few places where I was explicitly asking for Helvetica Neue, so I replaced those calls with asks for the system font.

Unfortunately, 2.2.0 also broke the in-app purchase for the ad disabler. Folks who already bought the ad disabler still had ads disabled, but people who didn’t already have it couldn’t buy it.

How did this happen? Didn’t I say in my last post that I have a Runbook that I use to test every part of the app? Yes, and I ran it for 2.2.0, and every other part of the app worked, but the store didn’t, and I shipped anyway. Why? Because I couldn’t find any reason in the code for the purchases not to work, so I decided to bet that I wasn’t able to do purchases in dev because the sandbox iTunes Store was down, which is something that happens from time to time. Once the app went live and purchases didn’t work with the real App Store, I knew that bet was wrong.

After poking around for a long time, I discovered the bug appeared when I transitioned to Swift 1.2. That version of Swift added a built-in Set type, and calls that used to take the Objective-C NSSet type changed to take the new Set type, so I changed one line of code in the store from:

SKProductsRequest(productIdentifiers: NSSet(array: identifiers))


SKProductsRequest(productIdentifiers: Set<NSObject>(arrayLiteral: identifiers))

So all is good, yes? No. For some reason, despite the fact that the syntax is valid, and logging out the resulting set appeared fine, for whatever reason when that bridged back to Objective-C for StoreKit, the set was invalid in some way, and a “could not connect to the iTunes Store” error would be produced. The solution ended up being to change the line to:

SKProductsRequest(productIdentifiers: Set(identifiers))

Which also compiles fine and looks fine when logged out, and by all respects should be functionally identical to the previous line, but it was the difference between a working store and a broken one. I’m guessing there’s a Swift bug here, and when I update the app to Swift 2.0 I think I’m going to try both constructions and see if only one still works, and if so file a bug.

So the lesson I need to take away from this is that I really do need to pass all my QA checks before shipping an app, no matter what.