@available, #available

• #available - 用於 code block

• @available - 用於 method 或 class 前面

💈範例

// ⭐️ if #available
// iOS 13 or later    any other unknown platforms announced in the future
//         ↳  ╭────╮  ↑
if #available(iOS 13, *) {
    // use UICollectionViewCompositionalLayout
} else {
    // show sad face emoji
}

// ⭐️ guard #available
guard #available(iOS 13, *) else { return }

// ⭐️ @available
@available(iOS 11, macOS 10.13, *)
func newMethod() {
    // Use iOS 11 APIs.
}

#if os(iOS)
var body: some View {
    NavigationView{ ... }
    .navigationViewStyle(StackNavigationViewStyle())
}
#else
var body: some View {
    NavigationView{ ... }
    .navigationViewStyle(DoubleColumnNavigationViewStyle())
}
#endif

🖥️ 影片

iOS Academy ⟩ Checking Availability in Swift

📗 參考

• ChatGPT ⟩

  • 如何使用自製 Swift Package

  • Xcode API 版本問題 ⭐️

• Hacking with Swift - Availability checking in Swift

• Sarun ⟩

  • How to handle API Changes with @available

  • How to handle API Changes with #available

📘 手冊

• Swift Language Reference ⟩ Attributes

• Swift ⟩ Objective-C and C Code Customization

  • Marking API Availability in Objective-C

🗣 討論

• Compiler directives in SwiftUI for platform-specific attributes

👥 相關

• Bool. .iOS14 - static property.

• #if ... #else ... #endif

check iOS version

💈範例

// use case
Text("Hello, world!")
   .padding()
   .if(.iOS14) { $0.background(Color.red) }    // ⭐️ use case

🌀 .iOS14

extension Bool {
     /// ⭐️ Bool.iOS14
     static var iOS14: Bool {
         guard #available(iOS 14, *) else { return false }
         return true
     }
 }

📗 參考

• SwiftLee ⟩ How to create a Conditional View Modifier in SwiftUI

👥 相關

• view.if(_:then:)