As much as you try to try everything and despite how well Apple is doing this summer with its flow of betas in preventing errors, nothing is 100% effective in software engineering. On the 10th, after Keynote, Apple published Xcode 11 GM, its final Golden Master version, which is basically the same one that will be published next 19 in the macOS App Store for download worldwide. However Apple releases these GM versions days before to finish validating these versions.
And these tests make sense when, suddenly, we find a fault like the one that has happened: that there was an error in the implementation of a feature when the apps were running on iOS 11 or earlier that has forced to urgently launch a patch to that final version : an Xcode 11 GM seed 2.
Color failure in iOS 11 or earlier
According to the information provided by Apple, an error was detected when using colors with names in the resource catalog , so that there could be an error in iOS 11 or earlier versions (if our app supports it) for which they returned a null value instead of the requested color when loading.
The GM versions of Xcode are the kick-off for developers in order to start submitting their updates for review with the new iOS 13 SDK, so that users can have all their new features on the day of its release to the public. But Apple has had to stop the uploads of the version it published on the 10th and only admit uploads with this latest seed 2 to avoid major backward compatibility issues with older iOS versions.
In a note on the developer website it says the following:
You can now upload your apps built with Xcode 11 GM seed 2 (11A420a) using the iOS 13 or watchOS 6 SDK to the App Store. Apps built with Xcode 11 GM seed (11A419c) cannot be uploaded to the App Store Connect. You should keep in mind that apps with Xcode 11 GM (11A419c) that use colors with names may experience flaws in their search (and return empty values) when running on iOS 11 or earlier. If you have uploaded an app that uses color names, you must rebuild it with Xcode 11 GM seed 2 (11A420a), try it on iOS 11 or earlier versions and upload it again to the App Store.
Therefore, all the apps that use these colors (which is one of the functions that allow the implementation of the dark mode, but that can also be used in previous versions by configuration) should be re-built with the new and patched version if they want Your update arrives correctly on 19.
To download this new version of Xcode 11 just go to the Apple developer portal and download it. Nothing else. On developer.apple.com. If you are developers it is important that you do it as soon as possible.