Xcode 12.5 RC Release Notes

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

Overview

Xcode 12.5 RC includes SDKs for iOS 14.5, iPadOS 14.5, tvOS 14.5, watchOS 7.4, and macOS Big Sur 11.3. The Xcode 12.5 Release Candidate supports on-device debugging for iOS 9 and later, tvOS 9 and later, and watchOS 2 and later. Xcode 12.5 RC requires a Mac running macOS Big Sur 11 or later.

General

New Features

You can create macOS File Provider extensions using the new File Provider Extension target template. (54054417)
The Reveal Build Products Folder item in the Product menu opens Finder and selects the folder where Xcode builds the product. (72248847)

Resolved Issues

Fixed an issue that could cause code completion, live issues, and other code-analysis features to produce incorrect results after you moved any of the source files of an open Xcode project. (57054858)
Large workspaces now open faster. (70276306)

Known Issues

Fixed an issue that could cause iOS 12.5, tvOS 14.5, watchOS 7.4, and earlier to set the minimum deployment target based on the app’s LSMinimumSystemVersion instead of its MinimumOSVersion. (76221112)

Deprecations

Don’t use the iOS MinimumOSVersion information property list key to declare the minimum release of macOS in which your app runs. Use LSMinimumSystemVersion instead. (73890473)
- Future releases of macOS ignore the MinimumOSVersion key in Mac apps, including apps built with Mac Catalyst.
- Future releases of macOS use the LSMinimumSystemVersion key in iOS apps built with Xcode 12.5 or later. If an iOS app doesn’t include an LSMinimumSystemVersion key, future releases of macOS compare the app’s MinimumOSVersion with the version of its Mac Catalyst runtime to determine compatibility.

Apple Clang Compiler

New Features

libc++ no longer honors the _LIBCPP_RAW_ITERATORS macro. Use wrapped iterators instead. (63088925)
Clang now infers the availability of +new from availability annotations on -init methods. Since +new calls [[Foo alloc] init], +new isn’t available unless +init is available. (75884815)

Build System

New Features

The build system no longer re-signs the hosting app target when building app-hosted test targets; instead it builds test targets before the app target’s sign task runs. This eliminates an extra codesign task, which speeds up builds for large apps with such test targets. (47322098)
xcodebuild now supports the -archive flag when creating an XCFramework, providing a shorthand method for creating an XCFramework from one or more archives. (64725832)

For example:
```
xcodebuild -archive <archive_path1> -framework MyFramework.framework -archive <archive_path2> -framework MyFramework.framework -o <output_xcframework_path>
```

Resolved Issues

Copy Files Build Phase now properly signs code for embedded frameworks with a framework version that isn’t “A”. (55701162) (FB7323980)
You can now manually reorder schemes. (61456142)
xcodebuild no longer double-escapes the output of xcodebuild -showBuildSettings -json. (63554669)
Preprocess and Assemble single-file actions now work correctly when analyze-while-building is enabled, and no longer display an empty property list in the source editor. (70811963)
Fixed a dependency cycle involving hosted test targets when Parallelize Build is disabled. Xcode no longer creates a cycle when the test target depends on another target in addition to the hosting target. (73210420)
The build system no longer emits a “duplicate tasks” error when both an app and a test target link with the same XCFramework. (74362639) (FB9005738)

Code Completion

New Features

Code completion is more reliable in expressions that contain errors, and in expressions that are ambiguous without additional context. (71378252)

For example, given:
```
func test(a: Int, b: String) -> Int { ... }
func test(a: Int, b: Int) -> String { ... }
func test(a: (Int, Int) -> Int) -> Int { ... }
```
Invoking code completion after test().prefix(3). suggests members of String. Invoking code completion after test(a: 2). suggests members of Int and String. Invoking code completion after $0. in the following block suggests members of Int:
```
test {
  $0.
}
```

Resolved Issues

Code completion now returns suggestions more quickly inside large function bodies. (58687608)

Debugging

New Features

When debugging C++ programs using libc++, LLDB now offers improved expression evaluation support for STL containers and algorithms. (19866497)
- You can call member functions of STL containers, even if they are never called in the target program.
- LLDB can instantiate templated functions from the standard library. This includes algorithms such as std::sort, std::count, std::count_if, and so on.

Resolved Issues

When debugging Swift code, Xcode’s variable view and the v (frame variable) command now display variables with resilient types including Foundation value types such as URL, URLComponents, Notification, IndexPath, Decimal, Data, Date, Global, Measurement, and UUID. (72101693)

Known Issues

Xcode fails to launch apps when Nightstand Mode is enabled on Apple Watch. (61351690)

Workaround: Disable Nightstand Mode on Apple Watch; Go to Settings > General > Nightstand Mode.

Instruments

New Features

<(start|end)-pattern> elements in os-signpost-interval schema are now optional. This allows Custom Instruments to match signposts by name and other properties without needing to specify the expected message format. (43850670)
Profiling XCTest with Instruments now automatically starts the recording, without a click on the record button. (50260328)
Instruments can now import os_log and os_signpost data from the ktrace files that include logging-level data. (56037733)
Custom Instruments can now specify statically defined sub-tracks without needing to be driven by table column data. (61367995)
xctrace export now produces output in time-sorted order. (69804348)
Table of Contents query for xctrace now exposes metadata information about the run. (71320853)

Resolved Issues

Fixed an issue where xctrace wouldn’t pass a standard input to the launched process. (17842765)
Launching an extension via Product > Profile in Xcode no longer causes Instruments to wait indefinitely for the process to start. (62275419) (FB7674284)
Fixed a crash that sometimes occurred when you started recording after transferring a Metal app from Xcode to Instruments. (70655385) (FB8824932)
Fixed an issue where plot elements wouldn’t draw using the color column specified in a point schema. (71680467) (FB8913696)

Known Issues

In macOS 11.2 or earlier, leaks and other command line analysis tools fail or crash when run against processes built with Mac Catalyst and processes running in iOS 14.5 or later on simulated devices. (74690398)

Interface Builder

New Features

You can now configure a Module for custom classes in the inspector for NSObjectController and similar objects. (35971498)

Resolved Issues

NSButton’s “Image Only” Position setting now properly displays an image without a title at runtime. (16200971)
Fixed an issue where the assistant editor wouldn’t display source code for a selected object’s custom Swift class if the class was annotated with @objc. (19623315)
Fixed an issue where connect-to-source wouldn’t properly escape Swift keywords in Outlet and Action names. (22527929)
Fixed an issue where Editor > Debug Selected Views failed to attach to @IBDesignable views for debugging. (45217745) (FB5645911)
Added Dark Mode support for the connect-to-source bindings popover. (47583413) (FB5701084)
Fixed iOS canvas appearance issues when importing project images with an unexpected scale. (63789933) (FB7719276)
Fixed an issue where the assistant editor could open the wrong source file for a selected object’s custom class if duplicate class names existed in the project. (67362709)
Fixed the canvas drifting when resizing the document outline. (67505701)
Fixed an issue where selecting the custom color item from an inspector’s color popup menu wouldn’t open the system colors picker window. (69365980) (FB8727901)
Selecting a view in the canvas and performing Select All (CMD+A) no longer selects the view’s layout guides. (69518746)
Fixed an issue where certain connect-to-source popover labels didn’t show up in Dark Mode. (69713404)
Fixed an issue where the custom colors swatch in an inspector’s color properties displayed an incorrectly offset focus indicator. (72370447)

Localization

New Features

You can now use Xcode to localize applications into all ISO 639 languages. (46806165) (FB5359472)
You can now use workspaces to export a collection of projects for localization, generating a single localization catalog for all projects in the workspace. As part of this change, options to import and export for localization are now in the Product menu instead of the Editor menu. You can also use xcodebuild -importLocalizations and xcodebuild -exportLocalizations with the -workspace option to export or import a workspace. (48548375)
The new Localization Export Supported build setting lets you disable localization export for a specific target or project that doesn’t require localization. (66606145)

Resolved Issues

Fixed an issue where the Application Language menu in the scheme editor doesn’t show all languages for which a project is localized. (28872507)
*-InfoPlist.strings files are now renamed to InfoPlist.strings at build-time for bundles that require Info.plist localization. This is consistent with existing behavior that renames Info.plist files at build-time. (38686398)
Exporting and importing for localization now produces an error if two files (ex: Main.strings and Main.storyboard) write translations to the same path. (39917359, 52412470) (FB6384066)
Fixed an issue where exporting color sets for localization caused Xcode to crash. (63934393)
Fixed an issue where new-style multiline Swift string literals weren’t properly extracted for localization. (64652467) (FB7742731)
Localizable keys in Info.plist files are now only automatically extracted on localization export for Application and App Extension targets. (66871236)
Fixed an issue where strings were replaced with their keys at localization export if the .strings file was outside the directory hierarchy of the Xcode project. (69835864) (FB8761502)

Playgrounds

New Features

A Playground in an app’s project can now access symbols from the app target. New playgrounds you create have this option on by default. To enable this functionality in existing playground documents, turn on the Import App Types option in the File Inspector. (66357893)
Inline results for deeply nested Swift arrays and structs now display more information in Xcode Playgrounds. (67344623)

Resolved Issues

Fixed an issue that could cause Xcode to show “No editor” when opening a Playground. (56484197)

Previews

Resolved Issues

The preferredColorScheme(_:) modifier now applies the theme to the nearest enclosing presentation, and its contained views. (62745457)

Signing and Distribution

Resolved Issues

Resolved an issue that prevented exporting distribution certificates from Xcode due to a keyboard focus issue in the authentication window. (71011727) (FB8880845)
Fixed an issue that caused OS X 10.11 and earlier to reject packages signed in macOS 11 or later. (71695608, 75599040)

Known Issues

Xcode doesn’t build projects with a signing certificate on a smart card, or that is accessed via a CryptoTokenKit extension. (58266781) (FB7516556)

Workaround: Instead of signing in Xcode or xcodebuild, run codesign in a post-build step.
OS X 10.11 or earlier may reject code signatures added to universal binaries by Xcode 12.5 running in macOS 11.2 or earlier. (70724583) (FB8830007)

Workaround: Specify --digest-algorithm=sha1,sha256 to the codesign utility at signing time. In Xcode, specify this using the OTHER_CODE_SIGN_FLAGS build setting.

Simulator

New Features

Simulator now supports recording video from within the app. Hold Option when clicking on the screenshot button in the toolbar (or press Command+R) to record a video. Click the red button to stop video recording. (63041314)
Simulator can create animated GIFs from video recordings using the new Record Video feature. After recording a video, right-click on the video preview, then select Save as Animated GIF. To keep both the video file and the animated GIF, press and hold Option and select Save Copy as Animated GIF. You can adjust the dimensions and size of the generated GIFs in Simulator Preferences. (65089299)

Known Issues

Siri isn’t available in simulated tvOS devices. (74261184, 75115292)
Simulator may not respect the I/O > Keyboard > Use the Same Keyboard Language as macOS setting. (74897431)

Source Control

Resolved Issues

Fixed an issue where some workspaces could fail to notice project file changes from source control operations until you quit and relaunched Xcode. (3920347)

Known Issues

If you rename the default branch in your remote repository and don’t update HEAD to point to the renamed branch, source code operations may fail and Xcode may return an error -100. (76070146)

Workaround: Use the git command line tool to re-point your HEAD; for example:
```
git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/<your_default_branch_name>
```

StoreKit

New Features

StoreKit Testing in Xcode now supports testing of non-renewing subscriptions. (59478394)
The StoreKit Test framework is now availabe on watchOS. (68152552)

Swift

New Features

Incremental compilation is faster in many cases. When you change code within the body of a struct, class, enum, protocol, or extension, Swift now recompiles far fewer files in that module than before. (51230617)
Implicit member expressions now support chains of member accesses. (57295228)

For example, this code is now valid:
```
let milky: UIColor = .white.withAlphaComponent(0.5)
let milky2: UIColor = .init(named: "white")!.withAlphaComponent(0.5)
let milkyChance: UIColor? = .init(named: "white")?.withAlphaComponent(0.5)
```
As is the case with the existing implicit member expression syntax, the resulting type of the chain must be the same as the (implicit) base, so it isn’t well-formed to write let cgMilky: CGColor = .white.withAlphaComponent(0.5).cgColor (unless appropriate white and withAlphaComponent members were defined on CGColor.).

Members of a “chain” can be properties, method calls, subscript accesses, force unwraps, or optional chaining question marks. Furthermore, the type of each member along the chain is permitted to differ (again, as long as the base of the chain matches the resulting type) meaning the following successfully typechecks:
```
struct Foo {
  static var foo = Foo()
  static var bar = Bar()

  var anotherFoo: Foo { Foo() }
  func getFoo() -> Foo { Foo() }
  var optionalFoo: Foo? { Foo() }
  subscript() -> Foo { Foo() }
}

struct Bar {
  var anotherFoo = Foo()
}

let _: Foo? = .bar.anotherFoo.getFoo().optionalFoo?.optionalFoo![]
```
Swift includes more checks when bridging data from Objective-C. In particular, the runtime library aborts your program with a suitable error message if it detects a non-nullable pointer that contains a null value. (58650899)
You can now use Float16 in code running on Apple silicon. (61937297)
Property wrappers are now supported on local variables. (73377111)
Functions, subscripts, and initializers may now have more than one variadic parameter. When using variadic parameters, also label the parameter immediately following a variadic parameter. (SE-0284, 73676506)

This makes declarations like the following valid:
```
func foo(_ a: Int..., b: Double...) { }

struct Bar {
  subscript(a: Int..., b b: Int...) -> [Int] { a + b }

  init(a: String..., b: Float...) { }
}
```

Property wrappers now work in local contexts. (74192307)

For example, this code is now valid:

@propertyWrapper
struct Wrapper<T> {
  var wrappedValue: T
}

func test() {
  @Wrapper var value = 10
}

When you run swift with no arguments, it starts a REPL (Read-Eval-Print Loop) that uses LLDB. The Swift compiler no longer contains the integrated REPL for compiler developers (formerly accessible by running swift -frontend -repl). (74613702)

The Swift compiler still supports running code as a script, for example:
```
swift myScript.swift
```
When compiling a type that conforms to a protocol via an extension, Swift takes into account the availability of the extension when forming generic types that use this protocol conformance. (74614358)

For example, consider a Box type whose conformance to Hashable uses features only available on macOS 11:
```
public struct Box {}

@available(macOS 11, *)
extension Box : Hashable {
  func hash(into: inout Hasher) {
    // call some new API to hash the value...
  }
}

public func findBad(_: Set<Box>) -> Box {}
// warning: conformance of 'Box' to 'Hashable' is only available in macOS 11 or newer

@available(macOS 11, *)
public func findGood(_: Set<Box>) -> Box {} // OK
```
In the above code, it isn’t valid for findBad() to take a Set<Box> because Set requires that its element type conform to Hashable, but the conformance of Box to Hashable isn’t available before macOS 11.

Note that using an unavailable protocol conformance is a warning, not an error, to avoid potential source compatibility issues. In prior releases, you could write code that made use of unavailable protocol conformances but worked anyway — if the optimizer had eliminated all runtime dispatch through this conformance, or the code in question was entirely unreachable at runtime.

Protocol conformances can also be marked as completely unavailable or deprecated, by placing an appropriate @available attribute on the extension:
```
@available(*, unavailable, message: "Not supported anymore")
extension Box : Hashable {}

@available(*, deprecated, message: "Suggest using something else")
extension Box : Hashable {}
```
If a protocol conformance is defined on the type itself, it inherits availability from the type. You can move the protocol conformance to an extension if you need it to have narrower availability than the type.

The @available attribute is no longer permitted on generic parameters, where it had no effect. (74614802)

For example:

struct Bad<@available(macOS 11, *) T> {}
// error: '@available' attribute can't be applied to this declaration

struct Good<T> {} // equivalent

Availability checking now rejects protocols that refine less available protocols. (74615650)

Previously, this was accepted by the compiler but could result in linker errors or runtime crashes; for example:
```
@available(macOS 11, *)
protocol Base {}

protocol Bad : Base {}
// error: 'Base' is only available in macOS 11 or newer

@available(macOS 11, *)
protocol Good : Base {} // OK
```
Protocol conformance checking now considers where clauses when evaluating if a typealias is a suitable witness for an associated type requirement. (74618612)

The following code is now rejected:
```
protocol Holder {
  associatedtype Contents
}

struct Box<T> : Holder {}
// error: type 'Box<T>' doesn't conform to protocol 'Holder'

extension Box where T : Hashable {
  typealias Contents = T
}
```
In most cases, the compiler would either crash or produce surprising results when making use of a typealias with an unsatisfied where clause, but it is possible that some previously-working code is now rejected. In the above example, the conformance can be fixed in one of the following ways:
- make it conditional (move the : Holder from the definition of Box to the extension)
- move the typealias from the extension to the type itself
- relax the where clause on the extension

Resolved Issues

Function overloading now works in local contexts, making the following valid:
```
func outer(x: Int, y: String) {
  func doIt(_: Int) {}
  func doIt(_: String) {}

  doIt(x)
  doIt(y)
}
```
In this code, the first doIt(_:) calls with an Int value, and the second with a String value. (29312676)
The runtime and compiler support for Swift’s is, as?, and as! operators has been overhauled, providing more consistent and predictable behavior. (58991956)
If your app (including loaded OS binaries) contains multiple redundant protocol conformances, Swift now uses the first one it finds in the first binary loaded (including in OS binaries). (72049977)
Fixed a crash that occurred when setting a value using a ReferenceWritableKeyPath that was upcast to a WritableKeyPath. (74191390) (FB8999603)

Known Issues

iOS Playgrounds may crash on initial execution. (70826934)

Workaround: Re-execute the Playground.

The compiler may generate incorrect code when you use an enum case with associated values to satisfy a protocol requirement. (72302307)

For example:

protocol FileHandlerAction {
  static func setFileURL(_ fileURL: NSURL) -> Self
}

enum AppAction : FileHandlerAction {
  case setFileURL(NSURL)
}

Workaround: Provide a static method to satisfy the requirement:

enum AppAction : FileHandlerAction {
  case _setFileURL(NSURL)

  static func setFileURL(_ fileURL: NSURL) -> Self {
    return ._setFileURL(fileURL)
  }
}

Deprecations

The Swift compiler emits a warning for the use of the await keyword as an unqualified identifier. Wrap await with back-ticks so Swift always treats it as an identifier, or fully qualify declarations named await. For example, add self anytime you reference an instance member named await from within the instance. (SE-0296, 67000350)

Swift Packages

New Features

Swift packages that specify a 5.4 tools version can now explicitly declare targets as executable, which allows the use of the @main keyword in package code. (SE-0294, 47691185)
The Swift Package Manager now builds package products and targets as dynamic frameworks automatically, if doing so avoids duplication of library code at runtime. (59931771) (FB7608638)
Swift Package Manager caches package dependencies on a per-user basis, which reduces the amount of network traffic and increases performance of dependency resolution for subsequent uses of the same package. If needed, you can disable cache use in xcodebuild by using the new -disablePackageRepositoryCache flag. (72204929)

Testing

New Features

XCTest now supports marking test failures as “expected”. Expected test failures don’t impact the overall pass/fail result of the suite containing the test. Xcode displays expected failures differently in the Test Navigator and Test Report, and highlights the line of code where the expected failure occurred along with an optional user description. Expected test failures provide a low-overhead tool for preserving the overall “green” state of a project’s test suite when there are failures which can’t be immediately resolved, ensuring that any new failures are clearly visible. In contrast to skipping a test with XCTSkip, a test with an expected failure still runs, reporting any unexpected changes. (13408632)

To mark a failure as expected, call the new XCTExpectFailure API in a test before the code which produces the test failure, for example:
```
XCTExpectFailure("…")
// Perform test which currently fails
```
Additionally, the scope of the expected failure can be limited by enclosing the failing code in a closure:
```
// Arrange and act on the test subject

XCTExpectFailure("…") {
    XCTAssert(…) // Failing assertion
}

// Continue test with further assertions etc.
```
By default, if XCTExpectFailure is called but the test doesn’t record a failure, XCTest marks the test as having failed due to an “unmatched expected failure”. This can be suppressed for failures which occur non-deterministically, by passing XCTExpectFailure an XCTExpectedFailure.Options object as a parameter, with its isStrict property set to false:
```
let options = XCTExpectedFailure.Options()
options.isStrict = false
XCTExpectFailure("…", options: options)
// Perform test which sometimes fails
```
Xcode now allows you to clean test results without having to re-open your workspace by selecting Clean Test Results from Xcode’s Product menu. (16527161)
Xcode now supports XCTest unit and UI tests for watchOS apps. When creating a new watchOS app, check the Include tests checkbox to add a unit and UI test target to the newly created project. For an existing project, add a unit or UI test target via File > New > Target, and then add the test target to the Test action of the WatchKit App scheme. To run the tests, select a watch simulator or device from the run destinations menu in the toolbar, and then choose Product > Test. Note that testing is supported on watchOS 7.4 or later. (21395998)
XCTest now automatically includes specialized subclasses of Swift generic test classes when running tests on macOS 11.3, iOS 14.5, tvOS 14.5, watchOS 7.4, or later OS versions. This allows you to use generics to improve reusability of test classes. (23493200)
XCTest now includes XCTAssertIdentical(_:_:_:file:line:) and XCTAssertNotIdentical(_:_:_:file:line:) APIs to assert whether two object instances are identical (the same instance) and are stricter than XCTAssertEqual by using the === operator instead of == in Swift. (46137782)
The code coverage report now shows the number of executable lines per file. (68808019)

Resolved Issues

The message String parameter of XCTSkip.init(_:file:line:) no longer includes @autoclosure incorrectly. Unlike its conditional variants XCTSkipIf and XCTSkipUnless, XCTSkip’s initializer unconditionally evaluates its message string. (63827685)
If a test times out (due to having Test Timeouts enabled in the active Test Plan), any content that the test emitted to standard out or standard error prior to the timeout is now included in the test log. (64591225)
Xcode and xcodebuild now prevent the computer from sleeping while executing tests. (67493488)
If code under test crashes, and Xcode is able to collect a crash report, the error message that Xcode generates in the Test Report and Test Log includes the crashing symbol, as well as the Application Specific Information field from the crash report. (69755517)
Fixed an issue where methods on XCTOSSignpostMetric threw an exception on watchOS. (72552791)
Xcode no longer incorrectly reports a name that starts with “” for tests that the test code dynamically generates at runtime. (73767460)

Known Issues

When running on a Mac with Apple silicon, Xcode doesn’t provide code coverage information for code in Swift packages. (71769076) (FB8919898)
If you run lengthy uninterrupted CPU-bound computation in a test on Apple Watch devices, watchOS may terminate the test runner. (74301580)

Workaround: Avoid performing heavy CPU-bound computation in your tests on Apple Watch devices.
Xcode crashes when you attempt to view test results for an integration. (76126769)

Workaround: Download the integration’s build logs and open the enclosed result bundle.

Deprecations

Xcode no longer includes XCTest’s legacy Swift overlay library (libswiftXCTest.dylib). Use the library’s replacement, libXCTestSwiftSupport.dylib, instead. For frameworks that encounter build issues because of the removal of the legacy library, delete the framework and library search paths for libswiftXCTest.dylib and add the ENABLE_TESTING_SEARCH_PATHS=YES build setting. This setting automatically sets the target’s search paths so that it can locate the replacement XCTest library. (70365050)