Just ahead of the public rollout, Apple has made the gold master versions of iOS 10, macOS Sierra, watchOS 3 and tvOS available for users for compatible devices. GM that stands for Gold Master is the final firmware before Apple pushes out the update to public. The GM seed is usually the same as the public release version.
The iOS 10 GM seed bumps the build version for your iPhone and iPad to 14A403, macOS Sierra to 16A319, 14S326 for watchOS 3 and 14T330 for tvOS 10. The company has also released Xcode 8 GM seed with build version 8A218a.
Xcode includes the latest toolset and Software development Kit (SDKs) for creating apps that can run on the latest version of an operating system. This means developers can build their apps using Xcode 8 GM seed and test them with the GM of macOS Sierra, iOS 10, watchOS 3 and tvOS 10 and submit their reviews to Apple.
The GM seeds for the respective OS versions are available as OTA updates. If you have earlier beta software running on your compatible devices that are registered with Apple Developer Program membership, you should receive the GM build via OTA update. Do not forget to create a backup of your iDevice before you go ahead and download the GM update.
To manually get the GM update, connect your iPhone, iPad to the internet over WiFi. Head over to Settings>> General>> Software update then tap Download and Install .
Apple has already confirmed that the final update to iOS 10 will start rolling out to iPhone and iPad users on 13 September, whereas eligible Mac computers will receive macOS Sierra on 20 September. The watchOS, as Apple notes on its websites, is coming this fall, without any details on the release date.