修复 SwiftUI Preview 项目中无法运行的问题

Posted on 2023-10-23 Edited on 2024-07-25

第一步：定位问题

页面	Scheme Target	Preview是否成功
空白View	App	失败
空白View	Package	成功
空白View + import Core	Package	成功
空白View + import Core + 调用Font	Package	失败

定位到时Common中Core的错误

第二步：分析解决问题

分析Common中Product：Core依赖没有真正引入。

故拆分Common为四个Product，直接对外暴露，解决了Preview无法运行的问题。

import PackageDescription

let package = Package(
    name: "Common",
    platforms: [
        .iOS(.v14)
    ],
    products: [
        .library(
            name: "Core",
           // type: .dynamic,
            targets: ["Core"]
        ),
    ],

有两个细节要调整：

全局Package移除 type: .dynamic，让SPM决定使用什么类型。
Fork ProgressHUD，移除 type: .static。并在Common Package.swift 中引用fork

1 2	// .package(url: "https://github.com/relatedcode/ProgressHUD.git", from: "13.7.2") .package(url: "https://github.com/gewill/ProgressHUD.git", branch: "devlop")

为什么改为静态库？

静态库可以避免Core引用的重复的问题。

Showing Recent Messages
Swift package target 'Core' is linked as a static library by 'AppCommoms' and 'Core', but cannot be built dynamically because there is a package product with the same name.

Swift package target 'Core' is linked as a static library by 'Onboarding' and 'Core', but cannot be built dynamically because there is a package product with the same name.

Swift package target 'Core' is linked as a static library by 'AppSDK' and 'Core', but cannot be built dynamically because there is a package product with the same name.

第三步：解决跨Package引用资源文件的问题

SwiftUI Preview 位置特殊处理

由于Preview特殊机制，实际上Bundle(for: BundleFinder.**self**).resourceURL，位置在 /Users/will/Library/Developer/Xcode/DerivedData/App-gvnjpztkrklpjvfegxsksaoxjaaf/Build/Intermediates.noindex/Previews/Onboarding/Products/Debug-iphonesimulator/PackageFrameworks/Onboarding_-570F2A58E471CBF3_PackageProduct.framework

需要往上跳两级目录。故在AppCommomsBundle 的Bundle备选中添加SwiftUI Preview目录即可。

private class BundleFinder {}

class AppCommomsBundle {
    static var module: Bundle = {
        // Bundle name should be like this "ProductName_TargetName"
        let bundleName = "AppCommoms_AppCommoms"
        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: BundleFinder.self).resourceURL,
            
            // SwiftUI Preview
            Bundle(for: BundleFinder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent(),
            
            // For command-line tools.
            Bundle.main.bundleURL
        ] + Bundle.allBundles.map { $0.bundleURL }
        
        for candidate in candidates {
            let bundlePath = candidate?.appendingPathComponent(bundleName + ".bundle")
            if let bundle = bundlePath.flatMap(Bundle.init(url:)) {
                return bundle
            }
        }
        return Bundle(for: BundleFinder.self)
//        fatalError("unable to find bundle named \(bundleName)")
    }()
}

使用`Bundle.module`

还有一种更简单的方案就是用Apple推荐的Bundle.module，也是Rswift使用的public let R = _R(bundle: Bundle.module)。

Access a resource in codein page link
Always use Bundle.module when you access resources. A package shouldn’t make assumptions about the exact location of a resource.

具体原因见Xcode Build生成的资源文件：

import class Foundation.Bundle
import class Foundation.ProcessInfo
import struct Foundation.URL

private class BundleFinder {}

extension Foundation.Bundle {
    /// Returns the resource bundle associated with the current Swift module.
    static let module: Bundle = {
        let bundleName = "Onboarding_Onboarding"

        let overrides: [URL]
        #if DEBUG
        // The 'PACKAGE_RESOURCE_BUNDLE_PATH' name is preferred since the expected value is a path. The
        // check for 'PACKAGE_RESOURCE_BUNDLE_URL' will be removed when all clients have switched over.
        // This removal is tracked by rdar://107766372.
        if let override = ProcessInfo.processInfo.environment["PACKAGE_RESOURCE_BUNDLE_PATH"]
                       ?? ProcessInfo.processInfo.environment["PACKAGE_RESOURCE_BUNDLE_URL"] {
            overrides = [URL(fileURLWithPath: override)]
        } else {
            overrides = []
        }
        #else
        overrides = []
        #endif

        let candidates = overrides + [
            // 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: BundleFinder.self).resourceURL,

            // For command-line tools.
            Bundle.main.bundleURL,
        ]

        for candidate in candidates {
            let bundlePath = candidate?.appendingPathComponent(bundleName + ".bundle")
            if let bundle = bundlePath.flatMap(Bundle.init(url:)) {
                return bundle
            }
        }
        fatalError("unable to find bundle named Onboarding_Onboarding")
    }()
}