Update your apps to use new features, and test your apps against API changes.
- Xcode 10.2+
- watchOS 5.2+
The watchOS 5.3 SDK provides support for developing watchOS apps for Apple Watch devices running watchOS 5.3. The SDK comes bundled with Xcode 10.3 available from the Mac App Store. For information on the compatibility requirements for Xcode 10.3, see Xcode 10.3 Release Notes.
Devices running watchOS 5.3 don’t appear as available for development in Xcode 10.2.1. (50638444)
Workaround: Run the following command in Terminal: