Function Body Macros で、SwiftUI の View に Accessibility Identifier を自動付与する/Function Body Macros: Autogenerate accessibility identifiers for SwiftUI Views

本スライドは Ebisu.mobile #11 〜会場に入れなかったトークたち〜 で使用したスライドになります。

Transcript

1. STORES גࣜձࣾ Yuki Miida (@miichan_ocha) Ebisu.mobile #11 ʙձ৔ʹೖΕͳ͔ͬͨτʔΫͨͪʙ 2025೥ 9݄4೔ Function Body Macros ͰɺSwiftUI ͷ View ʹ Accessibility Identifier Λࣗಈ෇༩͢Δ
2. ࣗݾ঺հ - Yuki Miida - GitHub: mii-chan - X: @miichan_ocha - Ϩδάϧʔϓ / iOSΤϯδχΞ - 2025೥3݄ೖࣾ - ྘஡ 🍵 ͕޷͖Ͱຖ೔ҿΜͰ͍·͢ 2
3. Accessibility Identifier
4. Accessibility Identifier - UI ςετ࣌ʹ UI ཁૉΛಛఆ͢ΔͨΊͷςετ༻ Identifier 4 https://developer.apple.com/documentation/uikit/uiaccessibilityidentification/accessibilityidentifier
5. ྫ: Button ͷಛఆํ๏ 1. Ϙλϯͷϥϕϧ໊Λࢦఆ 2. Ϙλϯʹ෇͚ͨ Accessibility Identifier Λࢦఆ 5
6. 1. Ϙλϯͷϥϕϧ໊Ͱಛఆ - Pros - Modifier Λ෇͚Δख͕͔͔ؒΒͳ͍ - Cons - ҆ఆੑ͕௿͍ - ಉҰը໘ͷϥϕϧ໊ॏෳͰࣦഊ - ϩʔΧϥΠζ͞Εͨจࣈྻ - ୺຤ͷݴޠઃఆมߋͰςετ͕յΕΔ 6
7. 2. Accessibility Identifier Ͱಛఆ - Pros - ҆ఆੑ͕ߴ͍ - Cons - Modifier Λ֤ View ʹ෇͚Δख͕͔͔ؒΔ 7
8. - ϚΫϩͰ accessibilityIdentifier Modifier Λࣗಈ෇༩ - Identifier: TypeName_label - ϥϕϧ໊ΑΓিಥ཰͕௿͍ɺϩʔΧϥΠζ͞Εͯ΋҆ఆ ࠓճ΍Γ͍ͨ͜ͱ 8 ↓ΛϚΫϩͰࣗಈੜ੒
9. Function Body Macros (SE-0415)
10. Function Body MacroʢBody Macroʣ1/2 - طଘͷؔ਺ͷத਎Λॻ͖׵͑ΒΕΔ Swift Macro - Swift 6.0 ͔Β࢖͑Δ 10 https://github.com/swiftlang/swift-evolution/blob/main/proposals/0415-function-body-macros.md#proposed-solution @Logged func g(a: Int, b: Int) -> Int { return a + b } func g(a: Int, b: Int) -> Int { log("Entering g(a: \(a), b: \(b))") defer { log("Exiting g") } return a + b }
11. Function Body MacroʢBody Macroʣ2/2 - Read-Only Computed Property ʹ΋෇༩Ͱ͖ΔΒ͍͠ - Proposalௐ΂ 11 https://github.com/swiftlang/swift-evolution/blob/main/proposals/0415-function-body-macros.md#proposed-solution
12. SwiftUI ͷ View ΁ͷద༻ - body property ʹ΋෇༩Ͱ͖Δʂʁ - ࠓճ͸ body ಺ͷશͯͷ Button ʹ accessibilityIdentifier Λࣗಈ෇༩͠·͢ 12 @SomeBodyMacro var body: some View { VStack { … }
13. Function Body Macro Λ࡞Δ
14. ৄࡉͳ࣮૷͸ԼهΛ͝ࢀর͍ͩ͘͞ https://github.com/mii-chan/UITestable 14
15. એݴํ๏ - @attached(body) Ͱએݴ 15 @attached(body) public macro UITestable() = #externalMacro( module: "UITestableMacros", type: "UITestableMacro" )
16. protocol BodyMacro Λ࣮૷͢Δ 16 /// Describes a macro that can create the body for a function that does not /// have one. public protocol BodyMacro: AttachedMacro { /// Expand a macro described by the given custom attribute and /// attached to the given declaration and evaluated within a /// particular expansion context. /// /// The macro expansion can introduce a body for the given function. static func expansion( of node: AttributeSyntax, providingBodyFor declaration: some DeclSyntaxProtocol & WithOptionalCodeBlockSyntax, in context: some MacroExpansionContext ) throws -> [CodeBlockItemSyntax] }
17. Step1. TypeName ͷ prefix Λ࡞Δ - context.lexicalContext ʹܕ৘ใ͕഑ྻͰೖ͍ͬͯΔ 17 /// The macro expansion can introduce a body for the given function. static func expansion( of node: AttributeSyntax, providingBodyFor declaration: some DeclSyntaxProtocol & WithOptionalCodeBlockSyntax, in context: some MacroExpansionContext ) throws -> [CodeBlockItemSyntax]
18. Step1. TypeName ͷ prefix Λ࡞Δ 18 private static func makeTypeHierarchyPrefix( from context: some MacroExpansionContext ) -> String { context.lexicalContext .compactMap { node in if let structDecl = node.as(StructDeclSyntax.self) { return structDecl.name.text } return nil } .reversed() .joined(separator: "_") }
19. Step2. body ಺ͷ Button ʹ Modifier Λ෇༩ - SyntaxRewriter Λ࢖͏ 19 final class ButtonModifierRewriter: SyntaxRewriter { override func visit( _ node: FunctionCallExprSyntax ) -> ExprSyntax { // Detect Button call guard let buttonCall = findButtonCall(node) else { return super.visit(node) } … }
20. Step2. body ಺ͷ Button ʹ Modifier Λ෇༩ 20 https://swift-ast-explorer.com/ Λ࢖༻
21. Step2. body ಺ͷ Button ʹ Modifier Λ෇༩ - Modifier chain ͷ్தͷ৔߹͸εΩοϓ͢Δ 21 // Skip if in the middle of a modifier chain if let parent = node.parent, parent.is(MemberAccessExprSyntax.self) { return super.visit(node) }
22. Step2. body ಺ͷ Button ʹ Modifier Λ෇༩ 22 let newExpr = FunctionCallExprSyntax( calledExpression: MemberAccessExprSyntax( base: ExprSyntax(node), period: .periodToken(leadingTrivia: newlineIndent), name: .identifier("accessibilityIdentifier") ), leftParen: .leftParenToken(), arguments: LabeledExprListSyntax { LabeledExprSyntax( expression: ExprSyntax(StringLiteralExprSyntax(content: "\(typeHierarchyPrefix)_\(label)")) ) }, rightParen: .rightParenToken() ) return ExprSyntax(super.visit(newExpr))
23. ϚΫϩΛ࢖ͬͯΈΑ͏
24. SwiftUI ͷ body property ʹϚΫϩΛ෇͚ͯΈΔͱ... 24
25. ݱঢ় Read-Only Computed Property ʹ͸෇༩Ͱ͖ͳ͍Β͍͠ 25 https://github.com/swiftlang/swift/ issues/75715
26. body Λؔ਺Խ͢Δ 26
27. Build Succeeded 27
28. ϚΫϩΛల։ͯ͠ΈΔ 28
29. ϚΫϩల։݁Ռ 29 ࣗಈ෇༩͞ΕͯΔʂ
30. UIςετͰ΋࢖͑ͨʂ 30
31. UIςετͰ΋࢖͑ͨʂ 31
32. ·ͱΊ - Function Body Macro Ͱ Modifier Λࣗಈ෇༩Ͱ͖ͨ - ৭ʑศརʹ׆༻Ͱ͖Δέʔε͕͋Γͦ͏ - طଘͷؔ਺ͷத਎Λॻ͖׵͑ΔͷͰ΍Γ͗͢ʹ͸஫ҙ - Կ͔ςετɾσόοά༻ͷػೳΛ଍ͯ͠ #if DEBUG Ͱғͬͯ࢖ͬͨΓ͢ Δͷ͸ྑ͍׆༻ํ๏͔΋ - Read-Only Computed Property ͕ରԠ͞ΕΔͱྑ͍ͳ 🙏 32
33. ͋Γ͕ͱ͏͍͟͝·ͨ͠ʂ