[SwiftCraft '24] Back to the Future: Swift 6 Edition!

The next major version of Swift is expected to bring several major changes to the language to make it safer and more developer-friendly.
While some of these features will greatly improve our experience as Swift developers, they will also introduce breaking changes and compatibility issues. That's why I put together this talk, where I will outline and explain all the upcoming and show you, with plenty of code examples, what you can start doing now to get ready for Swift 6.

Transcript

1. SWIFT 6 EDITION B a ck t o t h e f ut ur e
2. App maker and content creator based in Barcelona Hi! I’m Pol
4. A n n o u ncemen t H el m I s s hi p p i n g T o d a y ! Whe n A p p l e ap p rov e i t!
5. polpiella.dev
9. S wi f t 6 H ow t o get r e a d y f o r
11. 6.0.0 M a jo r v er sio n B r e a k i ng c h a nge s P a t c h v er sio n B ug f i x e s , et c . M i no r v er sio n N o n - br e a k i ng c o n sid er a bl e c h a nge s
12. 6.0.0 P n B c M n N s M a jo r v er sio n B r e a k i ng c h a nge s
13. S w if t 6 SE-0270 SE-0364 SE-0408 SE-0410 SE-0416 SE-0418 SE-0421 SE-0412 SE-0411 SE-0286 SE-0274 SE-0220 SE-0301 SE-0405 SE-0409 SE-0420 SE-0422 SE-0384 SE-0383 SE-0401 SE-0337 SE-0354 SE-0352 SE-0414 SE-0426
14. S w if t 6 SE-0270 SE-0364 SE-0408 SE-0410 SE-0416 SE-0418 SE-0421 SE-0412 SE-0411 SE-0286 SE-0274 SE-0220 SE-0301 SE-0405 SE-0409 SE-0420 SE-0422 SE-0384 SE-0383 SE-0401 SE-0337 SE-0354 SE-0352 SE-0414 SE-0426
18. S wift 6 Lan guag e M o d e !
20. h t t ps :// p o d c a s t s . a p p l e . c o m / u s / po d c a s t /43- now - i m - w o r r ie d - o ur - met r ics - a r en t - c o r r e c t - wi t h / i d 1654567329? i =1000653584114
21. S w if t 6 SE-0270 SE-0364 SE-0408 SE-0410 SE-0416 SE-0418 SE-0421 SE-0412 SE-0411 SE-0286 SE-0274 SE-0220 SE-0301 SE-0405 SE-0409 SE-0420 SE-0422 SE-0384 SE-0383 SE-0401 SE-0337 SE-0354 SE-0352 SE-0414 SE-0426
22. S w if t 6 Wit ho u t t h e S wi ft 6 la n g ua ge mo d e S w if t 6 SE-0270 SE-0364 SE-0408 SE-0410 SE-0416 SE-0418 SE-0421 SE-0412 SE-0411 SE-0286 SE-0274 SE-0220 SE-0301 SE-0405 SE-0409 SE-0420 SE-0422 SE-0384 SE-0383 SE-0401 SE-0337 SE-0354 SE-0352 SE-0414 SE-0426
24. S wi f t 6 H ow t o get r e a d y f o r t he L a n g u a ge mo d e
25. D own l o a d i n g S wi ft 6
28. #! /bin/sh # Install `swiftenv` brew install kylef/formulae/swiftenv echo 'if which swiftenv > /dev/null; then eval "$(swiftenv init -)"; fi' >> ~/.zshrc I n s t a l l o n m a c OS
29. #! /bin/sh # Install `swiftenv` brew install kylef/formulae/swiftenv echo 'if which swiftenv > /dev/null; then eval "$(swiftenv init -)"; fi' >> ~/.zshrc # Install the latest Swift 6 development toolchain swiftenv install 6.0-DEVELOPMENT-SNAPSHOT-2024-04-30-a I n s t a l l o n m a c OS
30. #! /bin/sh # Install `swiftenv` brew install kylef/formulae/swiftenv echo 'if which swiftenv > /dev/null; then eval "$(swiftenv init -)"; fi' >> ~/.zshrc # Install the latest Swift 6 development toolchain swiftenv install 6.0-DEVELOPMENT-SNAPSHOT-2024-04-30-a # CD into your Swift package directory cd your-swift-package # Set the Swift 6 toolchain as the default for this directory swiftenv local 6.0-DEVELOPMENT-SNAPSHOT-2024-04-30-a I n s t a l l o n m a c OS
31. #! /bin/sh # Install swiftly curl -L https: // swift-server.github.io/swiftly/swiftly-install.sh | bash # Install the latest Swift 6 development toolchain swiftly install 6.0-DEVELOPMENT-SNAPSHOT-2024-04-30-a # Set the Swift 6 toolchain as the active toolchain swiftly use 6.0-DEVELOPMENT-SNAPSHOT-2024-04-30-a I n s t a l l o n l i n ux
32. class NonIsolated { func callee() async {} } actor Isolated { let nonIsolated = NonIsolated() func callee() async { await nonIsolated.callee() } }
34. / / swift-tools-version: 6.0 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v10_15), .iOS(.v13)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"] ) ], targets: [ .target(name: "Swift6Examples") ], swiftLanguageVersions: [.version("6")] )
35. / / swift-tools-version: 6.0 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v10_15), .iOS(.v13)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"] ) ], targets: [ .target(name: "Swift6Examples") ], swiftLanguageVersions: [.version("6")] )
36. swift build -Xswiftc -swift-version -Xswiftc 6
38. I HAVE NO IDEA, I DON’T THINK YOU CAN
44. U p c o m i n g F e a t ur e s
45. h t t ps :// g i t h u b . c o m / a p p l e / s w i f t - e v o l u t io n / b l ob / m a i n / p r o p o s a ls /0362- p i e ce m e a l - f u t u r e - f e a t ur e s . md
48. // swift-tools-version: 6.0 import PackageDescription let package = Package( name: "UpcomingFeatures", products: [ .library( name: "UpcomingFeatures", targets: ["UpcomingFeatures"]), ], dependencies: [ ], targets: [ .target( name: "UpcomingFeatures", swiftSettings: [ .enableUpcomingFeature("InternalImportsByDefault") ] ) ] )
50. #if hasFeature(InternalImportsByDefault) fileprivate import MyDependency #else import MyDependency #endif
52. B r e a k i ng ch a n ge s A q ui ck t o ur o f t he swift 6 Lan g uag e M o d e !
53. h t t ps :// f o r u ms . swi ft . o r g / t / p r o gr e s s - t ow a r d - t h e - sw ift -6- l a ng u a ge - mo d e /68315
54. C o n cu r r enc y ch e ck i ng SE-0337
55. // swift-tools-version: 5.10 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v14)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableExperimentalFeature("StrictConcurrency") ] ) ] )
59. I t hi nk m a n y p e o p l e b el ie v e y o u t ur n o n c o mp l et e c h e ck i n g t o ge t p r ep a r e d f o r S w if t 6. A nd , y e s , t h a t is t r ue ! B u t , I d o n o t t h i nk t his i s t he mo s t c o mp el l i ng r e a s o n t o d a y . Y o u tur n o n c o mp l e t e che ck i n g t o l e a r n how S wi ft c o n c u r r en c y a c tu a l l y w o r k s . h t t p s :// w ww . m a ssi c o tt e . o r g / c o m p l et e - ch e ck i ng M a tt M a ss ic o t t e @ m a tt iem @ m a s t o d o n . s o ci a l
60. SE-0401 A c t o r i s o l a t io n p r o p er t y w r a p p e r s
61. final class Model: ObservableObject { let name: String init(name: String = "Hello!") { self.name = name } } struct MyView: View { @StateObject private var model = Model() var body: some View { Text("Hello, \(model.name)") .onAppear { viewAppeared() } } func viewAppeared() { updateUI() } } @MainActor func updateUI() { /* do stuff here * / } Non-is ol a t ed
62. final class Model: ObservableObject { let name: String init(name: String = "Hello!") { self.name = name } } struct MyView: View { @StateObject private var model = Model() var body: some View { Text("Hello, \(model.name)") .onAppear { viewAppeared() } } func viewAppeared() { updateUI() } } @MainActor func updateUI() { /* do stuff here * / } Iso la t e d t o t h e G lob al M ai n A c to r
63. final class Model: ObservableObject { let name: String init(name: String = "Hello!") { self.name = name } } struct MyView: View { @StateObject private var model = Model() var body: some View { Text("Hello, \(model.name)") .onAppear { viewAppeared() } } func viewAppeared() { updateUI() } } @MainActor func updateUI() { /* do stuff here * / } Iso la t e d t o M ain Ac t o r
64. final class Model: ObservableObject { let name: String init(name: String = "Hello!") { self.name = name } } struct MyView: View { @StateObject private var model = Model() var body: some View { Text("Hello, \(model.name)") .onAppear { viewAppeared() } } func viewAppeared() { updateUI() } } @MainActor func updateUI() { /* do stuff here * / } Iso la t e d t o M ain Ac t o r
65. // swift-tools-version: 5.10 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v14)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableExperimentalFeature("StrictConcurrency"), .enableUpcomingFeature(“DisableOutwardActorInference") ] ) ] )
67. // swift-tools-version: 6.0 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v14)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableExperimentalFeature("StrictConcurrency"), .enableUpcomingFeature("DisableOutwardActorInference"), .enableExperimentalFeature("RegionBasedIsolation"), .enableUpcomingFeature("IsolatedDefaultValues"), .enableUpcomingFeature("GlobalConcurrency"), .enableUpcomingFeature("InferSendableFromCaptures") ] ) ], swiftLanguageVersions: [.version("6")] )
68. SE-0274 C o n cis e m a gic f il e
69. public extension XCTestCase { func assertInstancesAreDeallocated( _ instances: [AnyObject], line: UInt = #line, file: StaticString = #file ) { let instancesContainer = NSHashTable<AnyObject>.weakObjects() instances.forEach { instancesContainer.add($0) } addTeardownBlock { instancesContainer.allObjects.forEach { XCTAssertNil($0, file: file, line: line) } } } }
70. public extension XCTestCase { func assertInstancesAreDeallocated( _ instances: [AnyObject], line: UInt = #line, file: StaticString = #file ) { let instancesContainer = NSHashTable<AnyObject>.weakObjects() instances.forEach { instancesContainer.add($0) } addTeardownBlock { instancesContainer.allObjects.forEach { XCTAssertNil($0, file: file, line: line) } } } }
72. // swift-tools-version: 5.8 import PackageDescription let package = Package( name: "Swift6Examples", products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .testTarget( name: "Swift6ExamplesTests", dependencies: ["Swift6Examples"], swiftSettings: [ .enableUpcomingFeature("ConciseMagicFile") ] ) ] )
73. #if hasFeature(ConciseMagicFile) / / In Swift 6 Language Mode XCTAssertEqual(#file, "Swift6ExamplesTests/Swift6ExamplesTests.swift") #else / / In Swift 5 Language Mode XCTAssertEqual( #file, "…/swift-6-swiftcraft/Tests/Swift6ExamplesTests/Swift6ExamplesTests.swift" ) #endif
74. #if hasFeature(ConciseMagicFile) / / In Swift 6 Language Mode XCTAssertEqual(#file, "Swift6ExamplesTests/Swift6ExamplesTests.swift") #else / / In Swift 5 Language Mode XCTAssertEqual( #file, "…/swift-6-swiftcraft/Tests/Swift6ExamplesTests/Swift6ExamplesTests.swift" ) #endif
76. R e gex l i t er a ls SE-0354
77. let pattern = #"WIFI:S:(?<ssid>[^;]+);( ?: T:(?<security>[^;]*);)?P:(?<password>[^;]+);( ?: H:(?<hidden>[^;]*);)?;"# let regularExpression = try! NSRegularExpression(pattern: pattern)
78. // swift-tools-version: 5.7 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v14)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableUpcomingFeature("BareSlashRegexLiterals") ] ) ] )
79. let regex = /WIFI:S:(?<ssid>[^;]+);( ? : T:(?<security>[^;]*);)?P:(?<password>[^;]+);( ?: H:(?<hidden>[^;]*);)?;/
80. SE-0286 T r a i l i ng cl o s ur e s
81. struct TestStructure { let firstClosure: ((String) -> Void)? let secondClosure: ((String, Int) - > Void)? init( firstClosure: ((String) -> Void)? = nil, secondClosure: ((String, Int) - > Void)? = nil ) { self.firstClosure = firstClosure self.secondClosure = secondClosure } }
82. struct TestStructure { let firstClosure: ((String) - > Void)? let secondClosure: ((String, Int) -> Void)? init( firstClosure: ((String) - > Void)? = nil, secondClosure: ((String, Int) -> Void)? = nil ) { self.firstClosure = firstClosure self.secondClosure = secondClosure } }
83. struct TestStructure { let firstClosure: ((String) - > Void)? let secondClosure: ((String, Int) -> Void)? init( firstClosure: ((String) - > Void)? = nil, secondClosure: ((String, Int) -> Void)? = nil ) { self.firstClosure = firstClosure self.secondClosure = secondClosure } } let a = TestStructure { a in print(a) }
84. struct TestStructure { let firstClosure: ((String) - > Void)? let secondClosure: ((String, Int) -> Void)? init( firstClosure: ((String) - > Void)? = nil, secondClosure: ((String, Int) -> Void)? = nil ) { self.firstClosure = firstClosure self.secondClosure = secondClosure } } let a = TestStructure { a in print(a) } let b = TestStructure { a, b in print(a, b) } War n in g!
85. // swift-tools-version: 5.10 import PackageDescription let package = Package( name: "Swift6Examples", platforms: [.macOS(.v14)], products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableUpcomingFeature(“ForwardTrailingClosures") ] ) ] )
86. struct TestStructure { let firstClosure: ((String) - > Void)? let secondClosure: ((String, Int) -> Void)? init( firstClosure: ((String) - > Void)? = nil, secondClosure: ((String, Int) -> Void)? = nil ) { self.firstClosure = firstClosure self.secondClosure = secondClosure } } let a = TestStructure { a in print(a) } let b = TestStructure { a, b in print(a, b) } let c = TestStructure(secondClosure: { a, b in print(a, b) }) Ok! Er r o r ! Ok!
87. I mp l i ci t O p en e xis t en t i a ls SE-0352
88. protocol WithSelfRequirement: Equatable {}
89. Er r o r ! protocol WithSelfRequirement: Equatable {} func testOpenExistential(selfRequirementProtocol: WithSelfRequirement) { }
90. protocol WithSelfRequirement: Equatable {} func testOpenExistential(selfRequirementProtocol: any WithSelfRequirement) { }
91. protocol WithSelfRequirement: Equatable {} func testOpenExistential(selfRequirementProtocol: any WithSelfRequirement) { }
92. protocol WithSelfRequirement: Equatable {} func requiresOpeningOfExistential<T: WithSelfRequirement>(openExistential: T) { } func testOpenExistential(selfRequirementProtocol: any WithSelfRequirement) { }
93. protocol WithSelfRequirement: Equatable {} func requiresOpeningOfExistential<T: WithSelfRequirement>(openExistential: T) { } func testOpenExistential(selfRequirementProtocol: any WithSelfRequirement) { requiresOpeningOfExistential(openExistential: selfRequirementProtocol) }
95. func printType<ExpectedType>(_ type: ExpectedType.Type) { print(type) } let type: any Any.Type = Int.self printType(type) Er r o r !
96. // swift-tools-version: 6.0 import PackageDescription let package = Package( name: "Swift6Examples", products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", swiftSettings: [ .enableUpcomingFeature(“ImplicitOpenExistentials”) ] ) ] )
97. SE-0383 d e p r e c a t e A p p l i c a t i o n m a i n
98. import AppKit @NSApplicationMain final class MyApplication: NSResponder, NSApplicationDelegate { // .. . } import UIKit @UIApplicationMain final class MyApplication: UIResponder, UIApplicationDelegate { // .. . }
99. import AppKit @NSApplicationMain final class MyApplication: NSResponder, NSApplicationDelegate { // .. . } import UIKit @UIApplicationMain final class MyApplication: UIResponder, UIApplicationDelegate { // .. . }
100. import AppKit @main final class MyApplication: NSResponder, NSApplicationDelegate { // .. . } import UIKit @main final class MyApplication: UIResponder, UIApplicationDelegate { // .. . }
101. // swift-tools-version: 5.10 import PackageDescription let package = Package( name: "Swift6Examples", products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], targets: [ .target( name: "Swift6Examples", swiftSettings: [ .enableUpcomingFeature("DeprecateApplicationMain") ] ) ] )
103. SE-0409 I n t er n a l i mpo r t s
104. import DependencyExample
105. private package public import DependencyExample internal fileprivate
107. // swift-tools-version: 5.9 import PackageDescription let package = Package( name: "Swift6Examples", products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], dependencies: [ ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableExperimentalFeature("AccessLevelOnImport"), ] ), .target(name: "DependencyExample") ] )
108. public import DependencyExample = = import DependencyExample Swi ft 5 la ngua ge m ode
109. public import DependencyExample = = import DependencyExample internal import DependencyExample = = import DependencyExample Swi ft 6 la ngua ge mo de Swi ft 5 la ngua ge m ode
110. // swift-tools-version: 6.0 import PackageDescription let package = Package( name: "Swift6Examples", products: [ .library( name: "Swift6Examples", targets: ["Swift6Examples"]), ], dependencies: [ ], targets: [ .target( name: "Swift6Examples", dependencies: ["DependencyExample"], swiftSettings: [ .enableExperimentalFeature("AccessLevelOnImport"), .enableUpcomingFeature("InternalImportsByDefault") ] ), .target(name: "DependencyExample") ] )
112. #! /usr/bin/swift private import Foundation let fileManager = FileManager.default let currentDirectory = fileManager.currentDirectoryPath let swiftFiles = fileManager.enumerator(atPath: currentDirectory)? .compactMap { $0 as? String } .filter { $0.hasSuffix(".swift") } for file in swiftFiles ?? [] { let filePath = "\(currentDirectory)/\(file)" guard let content = try? String(contentsOfFile: filePath) else { continue } let updatedContent = content .replacingOccurrences(of: #"import (\w+)"#, with: "public import $1", options: .regularExpression) try? updatedContent.write(toFile: filePath, atomically: true, encoding: .utf8) } h t t ps :// w w w . po l p iel l a . d ev / s wi f t -6- i mp o r t - a c ce ss - l ev el # a d o p t i ng - t he se - c h a n ge s
113. 👋 @_implementationOnly ?
114. SE-0384 O bj - c F o r w a r d d e cl a r a t i o n s
116. A l l br e a k i ng f e a tur e s SE-0274 F e a t ur e F l a g S wi ft 5.8 C o n c i s e M a gic F il e SE-0337 F e a t ur e F l a g S wi ft 5.6 S t r i c t c o n c ur r e nc y ch e ck i ng SE-0383 F e a t ur e F l a g S wi ft 5.10 D e p r e c a t e A p p l i c a t io n M a i n SE-0401 F e a t ur e F l a g S wi ft 5.9 D is a bl e O ut w a r d A c t o r I nf er en ce SE-0352 F e a t ur e F l a g S wi ft 6. o I mp l i ci t O p en E xis t e n t i a l s SE-0418 F e a t ur e F l a g S wi ft 6.0 I n f er S en d a b l e F r o m C a p tu r e s SE-0409 F e a t ur e F l a g S wi ft v er sio n 6.0 I n t e r n a l I m p o r t s B y D ef a ul t E xp e r i m en t a l f e a tu r e S wi ft 5.9 A c c e ss L e v e l O n I mpo r t SE-0384 F e a t ur e F l a g S wi ft 5.9 I m po r t O bj c F o r w a r d D e c l a r a t i o ns SE-0411 F e a t ur e F l a g S wi ft 5.10 I s o l a t ed D e f a ul t V a l u e s SE-0286 F e a t ur e F l a g S wi ft 5.8 F o r w a r d T r a i l i n g C l o s ur e s SE-0354 F e a t ur e F l a g S wi ft 5.8 B a r e S l a sh R e gex L i t er a ls SE-0412 F e a t ur e F l a g S wi ft v er sio n 5.10 G l o b a l C o ncur r enc y E xp e r i m en t a l f e a tu r e S wi ft 5.10 G l o b a l C o ncur r enc y
117. T h a n k YOU! A n y q ue s t io n s ? Dow n loa d He l m Fin d me o n l i ne !