Update your apps to use new features, and test your apps against API changes
Xcode 11.3 supports developing apps for iOS 13.3, iPadOS 13.3, tvOS 13.3, watchOS 6.1, and macOS Catalina 10.15.2. Xcode 11.3 supports on-device debugging for iOS 8 and later, tvOS 9 and later, and watchOS 2 and later. Xcode 11.3 requires a Mac running macOS Mojave 10.14.4 or later.
You can configure the Touch Bar simulator to simulate either 1st generation or 2nd generation Touch Bars. (53885368)
When you create an Objective-C category file by choosing File > New > File…, the newly created file includes an import of the AppKit framework. This causes a compilation error for iOS, tvOS, and watchOS. (55977950) (FB7346800)
Workaround: Remove the import of AppKit from the source file.
A Recommender template is available in Create ML, joining the Image, Sound, Activity, Text and Tabular Classification, Object Detection, Word Tagging and Tabular Regression templates. (56912822)
The color picker panel does not respond to choosing a color while a text field in the inspector has insertion focus. (56067005) (FB7358220)
Workaround: Click the Interface Builder canvas to remove focus from the text field, then choose a color in the panel.
Setting the Selected Segment Tint Color of a segmented control in Interface Builder to a named color doesn’t cause a failure when the view loads on iOS 12 and earlier. (55254963, 55951374)
Fixed rendering issues for scenes with large simulated metric free-form sizes. (56920189)
Xcode Previews now use a platform-provided scroll view for the canvas content when running on macOS Catalina 10.15.2 or newer. This change makes it possible to scroll through the canvas using a scroll wheel on a mouse, as well as by dragging horizontal and vertical scrollbars. (53962570)
Third party “endpoint security” software may cause slow simulators, system freezes, or prevent debug processes from running in simulators reliably. This sometimes manifests as
debugserverdisconnections, or sends simulator applications a
Workaround: Uninstall the third party software.
Under certain network conditions, GateKeeper may block simulators from booting, and show error code 60
“launchdfailed to respond.” (55878667)
Workaround: Try to boot the simulator again. Disabling WiFi or disconnecting from any active VPNs may resolve the problem.
When a new Mac Pro has multiple GPUs, Simulator assigns each booted simulator to one of the available GPUs. (56488185)
You can now submit iOS, tvOS, or watchOS apps with a Swift Package that builds a dynamic library. (55564324) (FB7303066)