Xcode 12.3 RC Release Notes

Update your apps to use new features, and test your apps against API changes.

Overview

Xcode 12.3 RC includes SDKs for iOS 14.3, iPadOS 14.3, tvOS 14.3, watchOS 7.2, and macOS Big Sur 11.1. The Xcode 12.3 release candidate supports on-device debugging for iOS 9 and later, tvOS 9 and later, and watchOS 2 and later. Xcode 12.3 RC requires a Mac with Apple silicon running macOS Big Sur 11 or later, or an Intel-based Mac running macOS Catalina 10.15.4 or later.

General

Resolved Issues

• Improved responsiveness of macOS mouse and keyboard events while under heavy load, such as when building a large project while running Simulator. (71819679)

Known Issues

• The first time you launch Xcode on a Mac with Apple silicon without Rosetta installed, Xcode prompts you to install Rosetta. The prompt prevents any interaction, and blocks Xcode from launching. (70853975) (FB8848625)

  Workaround: Launch an x86_64 process to trigger the system’s Rosetta prompt.

Build System

Resolved Issues

• Fixed an issue where xcodebuild sometimes logged unexpected output about failed event streams. (33401512)

Devices

Resolved Issues

• Fixed an issue that caused Xcode to spontaneously lose device configuration information for an Apple Watch. This data loss caused Xcode to either crash or display an error stating that your app “cannot be installed on (null)”. (54768855)

• Fixed an issue where Xcode could fail to prepare a wirelessly connected iOS device for debugging with the error “Failed _shouldMakeReadyForDevelopment check”. (61227501) (FB7649607)

• Fixed an issue that blocked simulator runtimes from being available when running command-line tools like simctl or xcodebuild from a non-root LaunchDaemon, or when launching as a different user from the current user (for example, with sudo or launchctl). (62188195, 69738053)

• Fixed an issue that could cause Xcode to get interrupted when copying symbols from iOS devices, and never finish preparing iOS devices for debugging. The failure mainly occurred on Xcode installations used to debug multiple iOS devices which are running the same version of iOS. This bug impacted the performance of launching executables on iOS devices and attaching the debugger to them. (68221778) (FB8611135)

Documentation Viewer

Resolved Issues

• Fixed a crash that could happen when opening the Documentation Window if you installed Xcode outside of /Applications. (70631583)

Interface Builder

Resolved Issues

• Fixed iOS storyboard rendering issues when using UISplitViewController simulated metric sizes with UITabBarController. (69054879) (FB8704013)

• Fixed an issue that caused Xcode to warn about multiple deprecated system color references in saved documents. (69667149) (FB8749086)

• Fixed an issue where the background color of a UITextField could appear transparent in your app instead of the default color. (70559650)

Simulator

New Features

• simctl now prints “Recording started” to stderr when it has enqueued the first frame of a video recording. Scripts or other automation can wait for that message before proceeding, to ensure the first part of the operation is captured in the resulting video. (57915463)

Resolved Issues

• simctl video recordings no longer cut off the end of the video when no screen updates are happening. The recording timeline now holds the last frame and extends until you terminate the recording with Control-C (SIGINT). (67952344) (FB8565355)

• CoreSimulator now excludes its caches directory from Time Machine backups by default. (68782191)

Known Issues

• When using macOS Big Sur 11.0 or 11.0.1 on your Mac, you can’t run a simulated device with watchOS 6, and you can’t run apps with 32-bit code in simulated devices running watchOS 7. This issue is fixed in macOS Big Sur 11.1. (69093569)

• Siri may not respond in a simulated device running on a Mac with Apple silicon. (71604992)

• Apps may not detect all game controller events when running in simulated devices on Macs with Apple silicon. (71651414)

Swift

Resolved Issues

• Fixed a failure that could occur when compiling a project with Mac Catalyst that imports OSLog from Swift. (68597591)