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Apple announced Swift 5 for Xcode 10.2 yesterday. The latest Swift 5 update in Xcode 10.2 explores new features and changes to App thinning, Swift Language, Swift Standard Library, Swift Package Manager, and Swift Compiler.

Swift is a popular general-purpose, compiled programming language developed by Apple Inc. for iOS, macOS, watchOS, tvOS, and beyond. Writing Swift code is interactive and its syntax is concise yet expressive. Swift code is safe and comprises all modern features.

What’s new in Swift 5 for Xcode 10.2?

In Xcode 10.2, the Swift command-line tools now require the Swift libraries in macOS. These libraries are included by default in Swift, starting with macOS Mojave 10.14.4.

App Thinning

Swift apps now no longer include dynamically linked libraries for the Swift standard library as well as the Swift SDK overlays in build variants for devices that run iOS 12.2, watchOS 5.2, and tvOS 12.2. This results in Swift apps getting smaller once they’re shipped in the App Store or thinned in an app archive for development distribution.


Swift Language

String literals in Swift 5 can be expressed with the help of enhanced delimiters. A string literal consisting of one or more number signs (#) before the opening quote considers backslashes and double-quote characters as literal. Also, Key paths can now support the identity keypath (\.self) i.e. a WritableKeyPath that refers to its entire input value.

Swift Standard Library

The standard library in Swift now consists of the Result enumeration with Result.success(_:) and Result.failure(_:) cases. Due to the addition of Standard Library, the Error protocol now conforms to itself and makes working with errors easier. The SIMD types and basic operators have now been defined in the standard library.

Set and Dictionary also make use of a different hash seed now for each newly created instance. The DictionaryLiteral type has been renamed as KeyValuePairs in Swift 5. The String structure’s native encoding has been switched from UTF-16 to UTF-8. This improves the relative performance of String.UTF8View as compared to String.UTF16View.

Swift Package Manager

Targets can now declare the commonly used, target-specific build settings while using the Swift 5 Package.swift tools-version. A new dependency mirroring feature in Swift 5 enables the top-level packages to override dependency URLs. Package manager operations have become significantly faster for larger packages.

Swift Compiler

Size taken up by Swift metadata can be reduced now as the Convenience initializers defined in Swift only allocates an object ahead of time in case its calling a designated initializer defined in Objective-C. C types consisting of alignment greater than 16 bytes are no longer available in Swift. Swift 3 mode has been deprecated.

Supported values for the -swift-version flag has become 4, 4.2, and 5.Default arguments can now be printed in SourceKit-generated interfaces for Swift modules.

For more information, check out the official Swift 5 for Xcode 10.2 release notes.

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