问题描述
只是玩 Swift UI 基本应用程序，即使我处于画布模式，预览画布也没有显示.应用程序运行，我有这个小片段我缺少什么?
Just playing with Swift UI basic app and the preview canvas is not showing even though I'm in canvas mode. App runs, and I have this little snippet what am I missing?
#if DEBUG
struct ContentView_Previews : PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
推荐答案
要在 Xcode 中预览画布中的视图并与之交互，请确保您的 Mac 在 Catalina MacOS 上运行.
To preview and interact with views from the canvas in Xcode, ensure your Mac is running on Catalina MacOS.
https://developer.apple.com/tutorials/swiftui/创建和组合视图
请查看以下网址中的苹果文档https://developer.apple.com/documentation/xcode_release_notes/xcode_11_beta_2_release_notes
Please check apple document in the following URLhttps://developer.apple.com/documentation/xcode_release_notes/xcode_11_beta_2_release_notes
Xcode 11 beta 支持使用 SwiftUI 进行开发.
注意
SwiftUI 开发工具仅在 macOS 上运行时可用Catalina 10.15 测试版.
Tools for SwiftUI development are only available when running on macOS Catalina 10.15 beta.
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