xcode - 从嵌套的 Swift 包访问 Assets 时，SwiftUI 预览会崩溃

Question

一个模块
我有一个具有两个结构的模块 (A)。

一种直接在代码中启动的颜色。

一种从 Assets 加载的颜色。

public struct CodeColor {
    public init() { }
    public let value = SwiftUI.Color(#colorLiteral(red: 0.8549019694, green: 0.250980407, blue: 0.4784313738, alpha: 1))
}

public struct AssetColor {
    public init() { }
    public let value = SwiftUI.Color("Legacy/Material/Gold", bundle: .module)
}

预览效果很好:


B模块
第二个模块 (B) 应使用前一个 (A) 作为依赖项从以下位置加载颜色:

import A

public struct CodeColor {
    public init() { }
    public var value: SwiftUI.Color { A.CodeColor().value }
}

public struct AssetColor {
    public init() { }
    public var value: SwiftUI.Color { A.AssetColor().value }
}

但是一旦它触及模块(A)中的 Assets ，预览崩溃:

🛑 错误:

Can not preview in this file. Failed to update preview.

RemoteHumanReadableError: Failed to update preview.

The preview process appears to have crashed.

Error encountered when sending 'previewInstances' message to agent.

==================================

|  RemoteHumanReadableError: The operation couldn’t be completed. (BSServiceConnectionErrorDomain error 3.)
|  
|  BSServiceConnectionErrorDomain (3):
|  ==BSErrorCodeDescription: OperationFailed

那是为什么？
注:奇怪的是，如果它在实际应用程序中(而不是另一个包)，则确切的 B 预览代码正在工作
Here is the full code on github

Answer 1

我在开发者论坛中找到了解决方案:
友情链接
https://developer.apple.com/forums/thread/664295?login=true#reply-to-this-question
注意 - 本地
解决方案是本地包。你定义

let bundleNameIOS = "LocalPackages_TargetName"
let bundleNameMacOs = "PackageName_TargetName"

远程(例如来自 GitHub 的包)
如果你在 GitHub 上有你的包并远程获取它，你不能定义本地包，你必须稍微改变它:

let bundleNameIOS = "TargetName_TargetName"
let bundleNameMacOs = "TargetName_TargetName"

示例
这是一个完整的实现示例，您必须将其与资源一起放入您的包中:

// Inside your package with the resources:
// Extend Bundle to access it in other packages
extension Bundle {

    // public static let assets = Bundle.module
    // Updated with workaround
    public static let assets = Bundle.myModule
    
}

定义您的捆绑包

private class CurrentBundleFinder {}
extension Foundation.Bundle {
    static var myModule: Bundle = {
        /* The name of your package. You may have same PackageName and TargetName*/
        let bundleNameIOS = "TargetName_TargetName"
        let bundleNameMacOs = "TargetName_TargetName"
        
        let candidates = [
            /* Bundle should be present here when the package is linked into an App. */
            Bundle.main.resourceURL,
            /* Bundle should be present here when the package is linked into a framework. */
            Bundle(for: CurrentBundleFinder.self).resourceURL,
            // -> Optional UI Tests
            /* Bundle should be present here when the package is used in UI Tests. */
            Bundle(for: CurrentBundleFinder.self).resourceURL?.deletingLastPathComponent(),
            /* For command-line tools. */
            Bundle.main.bundleURL,
            /* Bundle should be present here when running previews from a different package (this is the path to "…/Debug-iphonesimulator/"). */
            Bundle(for: CurrentBundleFinder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent().deletingLastPathComponent(),
            Bundle(for: CurrentBundleFinder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent(),
        ]
        
        for candidate in candidates {
            let bundlePathiOS = candidate?.appendingPathComponent(bundleNameIOS + ".bundle")
            let bundlePathMacOS = candidate?.appendingPathComponent(bundleNameMacOs + ".bundle")
            if let bundle = bundlePathiOS.flatMap(Bundle.init(url:)) {
                return bundle
            } else if let bundle = bundlePathMacOS.flatMap(Bundle.init(url:)) {
                return bundle
            }
        }
        fatalError("unable to find bundle")
    }()
}

访问包 B 中的包 A 资源
您现在可以从包 B 中的包 A 访问资源，例如:

let example = UIImage(named: "Exampe", in: Bundle.assets, with: nil)!