Update your apps to use new features, and test your apps against API changes.
The macOS 10.15.4 SDK provides support to develop apps for Macs running macOS Catalina 10.15.4. The SDK comes bundled with Xcode 11.4, available from the Mac App Store. For information on the compatibility requirements for Xcode 11.4, see Xcode 11.4 Release Notes.
Using a custom Mach service name is now supported for
XPCbetween apps and extensions. See EndpointSecurity for more information. (57244148)
The Music app now supports time-synced lyrics for Apple Music subscribers. (53877474)
Content Blocker extensions delivered with Mac Catalyst apps are now available for use in Safari. (43646265)