🤛 🤚🏽 👩‍👩‍👧 Swift Result Builders：説明とコード例 ✋🏽 🏴󠁧󠁢󠁷󠁬󠁳󠁿 🕒

翻訳は、コース「iOSDeveloper.Professional」のセットの一部として作成されました。

オープンデモレッスン「CoreMLとCreateMLを使用したiOSでの機械学習：画像、テキスト、サウンド」に皆様をご招待します。このレッスンでは、次のことについて説明します

。1。ニューラルネットワークの主なアーキテクチャとモバイルデバイス用に最適化されたバージョン。

2. CoreML 3および4の可能性、iOSデバイスでのトレーニング。

3. CreateMLを使用し、Visionで使用する画像分類器のセルフトレーニング。

4.トレーニング済みモデルを使用してiOSでテキストとサウンドを操作します。

(result builders) Swift — « ». Swift 5.4 Xcode 12.5 . function builders (« »). , , SwiftUI.

: , Swift, . UIKit, , .

?

- (DSL), . SwiftUI @ViewBuilder

, :

struct ContentView: View {
     var body: some View {
         // This is inside a result builder
         VStack {
             Text("Hello World!") // VStack and Text are 'build blocks'
         }
     }
 }

( VStack, Text

) View

. , « » View

«» View

. , .

View

SwiftUI, , body

@ViewBuilder

:

@ViewBuilder var body: Self.Body { get }

, .

, . :

var constraints: [NSLayoutConstraint] = [
     // Single constraint
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor)
 ]

 // Boolean check
 if alignLogoTop {
     constraints.append(swiftLeeLogo.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor))
 } else {
     constraints.append(swiftLeeLogo.centerYAnchor.constraint(equalTo: view.centerYAnchor))
 }

 // Unwrap an optional
 if let fixedLogoSize = fixedLogoSize {
     constraints.append(contentsOf: [
         swiftLeeLogo.widthAnchor.constraint(equalToConstant: fixedLogoSize.width),
         swiftLeeLogo.heightAnchor.constraint(equalToConstant: fixedLogoSize.height)
     ])
 }

 // Add a collection of constraints
 constraints.append(contentsOf: label.constraintsForAnchoringTo(boundsOf: view)) // Returns an array

 // Activate
 NSLayoutConstraint.activate(constraints)

, . .

— . :

 @AutolayoutBuilder var constraints: [NSLayoutConstraint] {
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor) // Single constraint
     
     if alignLogoTop {
         swiftLeeLogo.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
     } else {
         swiftLeeLogo.centerYAnchor.constraint(equalTo: view.centerYAnchor) // Single constraint
     }
     
     if let fixedLogoSize = fixedLogoSize {
         swiftLeeLogo.widthAnchor.constraint(equalToConstant: fixedLogoSize.width)
         swiftLeeLogo.heightAnchor.constraint(equalToConstant: fixedLogoSize.height)
     }
     
     label.constraintsForAnchoringTo(boundsOf: view) // Returns an array
 }

, ?

, .

AutolayoutBuilder

@resultBuilder

, :

@resultBuilder
 struct AutolayoutBuilder {     
     // .. Handle different cases, like unwrapping and collections 
 }

« » , , . .

 @resultBuilder
 struct AutolayoutBuilder {
     
     static func buildBlock(_ components: NSLayoutConstraint...) -> [NSLayoutConstraint] {
         return components
     } 
 }

components ( ). , . , .

@AutolayoutBuilder var constraints: [NSLayoutConstraint] {
     // Single constraint
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor)
 }

« »

. constraintsForAnchoringTo(boundsOf:)

, . , :

最初、カスタム結果ビルダーはコンポーネントのコレクションを処理できません。 — .

Cannot pass array of type ‘[NSLayoutConstraint]’ as variadic arguments of type ‘NSLayoutConstraint’ — «[NSLayoutConstraint]» «NSLayoutConstraint»

, Swift . . , :

, , , . , , .

, , NSLayoutConstraint

, :

 protocol LayoutGroup {
     var constraints: [NSLayoutConstraint] { get }
 }
 extension NSLayoutConstraint: LayoutGroup {
     var constraints: [NSLayoutConstraint] { [self] }
 }
 extension Array: LayoutGroup where Element == NSLayoutConstraint {
     var constraints: [NSLayoutConstraint] { self }
 }

, . , — [NSLayoutConstraint

].

, LayoutGroup

:

 @resultBuilder
 struct AutolayoutBuilder {
     
     static func buildBlock(_ components: LayoutGroup...) -> [NSLayoutConstraint] {
         return components.flatMap { $0.constraints }
     }
 }

flatMap

. , flatMap

compactMap

, compactMap flatMap: ?

, , « »:

@AutolayoutBuilder var constraints: [NSLayoutConstraint] {
     // Single constraint
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor)
     
     label.constraintsForAnchoringTo(boundsOf: view) // Returns an array
 }

, , — . , .

buildOptional(..)

:

 @resultBuilder
 struct AutolayoutBuilder {
     
     static func buildBlock(_ components: LayoutGroup...) -> [NSLayoutConstraint] {
         return components.flatMap { $0.constraints }
     }
     
     static func buildOptional(_ component: [LayoutGroup]?) -> [NSLayoutConstraint] {
         return component?.flatMap { $0.constraints } ?? []
     }
 }

, .

« »:

@AutolayoutBuilder var constraints: [NSLayoutConstraint] {
     // Single constraint
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor)
     
     label.constraintsForAnchoringTo(boundsOf: view) // Returns an array
     
     // Unwrapping an optional
     if let fixedLogoSize = fixedLogoSize {
         swiftLeeLogo.widthAnchor.constraint(equalToConstant: fixedLogoSize.width)
         swiftLeeLogo.heightAnchor.constraint(equalToConstant: fixedLogoSize.height)
     }
 }

— . . :

 @AutolayoutBuilder var constraints: [NSLayoutConstraint] {
     // Single constraint
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor)
     
     label.constraintsForAnchoringTo(boundsOf: view) // Returns an array
     
     // Unwrapping an optional
     if let fixedLogoSize = fixedLogoSize {
         swiftLeeLogo.widthAnchor.constraint(equalToConstant: fixedLogoSize.width)
         swiftLeeLogo.heightAnchor.constraint(equalToConstant: fixedLogoSize.height)
     }
     
     // Conditional check
     if alignLogoTop {
         // Handle either the first component:
         swiftLeeLogo.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
     } else {
         // Or the second component:
         swiftLeeLogo.centerYAnchor.constraint(equalTo: view.centerYAnchor)
     }
 }

« »:

 @resultBuilder
 struct AutolayoutBuilder {     
     static func buildBlock(_ components: LayoutGroup...) -> [NSLayoutConstraint] {
         return components.flatMap { $0.constraints }
     }
     
     static func buildOptional(_ component: [LayoutGroup]?) -> [NSLayoutConstraint] {
         return component?.flatMap { $0.constraints } ?? []
     }
     
     static func buildEither(first component: [LayoutGroup]) -> [NSLayoutConstraint] {
         return component.flatMap { $0.constraints }
     }
 
     static func buildEither(second component: [LayoutGroup]) -> [NSLayoutConstraint] {
         return component.flatMap { $0.constraints }
     }
 }

buildEither

LayoutGroup

.

, . !

. , .

— . AutolayoutBuilder

.

, NSLayoutConstraint

, :

extension NSLayoutConstraint {
     /// Activate the layouts defined in the result builder parameter `constraints`.
     static func activate(@AutolayoutBuilder constraints: () -> [NSLayoutConstraint]) {
         activate(constraints())
     }

NSLayoutConstraint.activate {
     // Single constraint
     swiftLeeLogo.centerXAnchor.constraint(equalTo: view.centerXAnchor)
     
     label.constraintsForAnchoringTo(boundsOf: view) // Returns an array
     
     // Unwrapping an optional
     if let fixedLogoSize = fixedLogoSize {
         swiftLeeLogo.widthAnchor.constraint(equalToConstant: fixedLogoSize.width)
         swiftLeeLogo.heightAnchor.constraint(equalToConstant: fixedLogoSize.height)
     }
     
     // Conditional check
     if alignLogoTop {
         // Handle either the first component:
         swiftLeeLogo.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
     } else {
         // Or the second component:
         swiftLeeLogo.centerYAnchor.constraint(equalTo: view.centerYAnchor)
     }
 }

, , UIView

:

 protocol SubviewContaining { }
 extension UIView: SubviewContaining { }
 extension SubviewContaining where Self == UIView {
     
     /// Add a child subview and directly activate the given constraints.
     func addSubview<View: UIView>(_ view: View, @AutolayoutBuilder constraints: (Self, View) -> [NSLayoutConstraint]) {
         addSubview(view)
         NSLayoutConstraint.activate(constraints(self, view))
     }
 }

 let containerView = UIView()
 containerView.addSubview(label) { containerView, label in
     
     if label.numberOfLines == 1 {
         // Conditional constraints
     }
     
     // Or just use an array:
     label.constraintsForAnchoringTo(boundsOf: containerView)
     
 }

, UIView

. , label

.

?

, , : , ?

, , , . , , .

, , . « », ( ) .

, ( ).

— Swift 5.4. - , . , , .

"iOS Developer. Professional"

«Machine Learning iOS CoreML CreateML: , , »

Swift Result Builders：説明とコード例

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« »

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