Xcode cannot generate Swift UI preview - build aborted due to an internal error: planningFailed

Question

我正在使用 Xcode 12 beta 2。我将我的库打包在 Swift 包中。出现在错误消息中的 DataModel 就是其中之一，我当前的包 WeatherView 取决于它。

我可以很好地构建包，但是 Swift UI 预览失败

build aborted due to an internal error: planningFailed("multiple configured targets of \'DataModel\' are being created for iOS Simulator")

----------------------------------------

SchemeBuildError: Failed to build the scheme "WeatherView"

unexpected service error: build aborted due to an internal error: planningFailed("multiple configured targets of \'DataModel\' are being created for iOS Simulator")

Build system information:
error: unexpected service error: build aborted due to an internal error: planningFailed("multiple configured targets of \'DataModel\' are being created for iOS Simulator")

Answer 1

我发现使产品库“动态”（而不是静态）使我的预览在包的目标内部工作。

let package = Package(
    name: "Modules",
    platforms: [
        .iOS(.v13)
    ],
    products: [
        .library(
            name: "Modules",
            type: .dynamic,
            targets: ["App"]
        ),
    ],
    dependencies: [],
    targets: [
        .target(
            name: "App",
            dependencies: []
        ),
        .testTarget(
            name: "AppTests",
            dependencies: ["App"]
        ),
    ]
)

还必须声明包的平台。

Answer 2

我在尝试预览我的 SwiftUI canvas 视图时遇到了同样的错误。我在 Xcode 中打开了多个选项卡。我关闭了所有其他选项卡，但我的视图和我的 canvas 预览又开始工作了。