SwiftPM Bundle Finding

gistfile1.txt

////////////////////////////////////
// Main bundle finding logic
import Foundation

public protocol BundleFinder: AnyObject {
    static var packageName: String { get }
    static var moduleName: String { get }
    static var packageModule: Bundle { get }
}

extension Bundle {
    private static var foundBundles: [String: Bundle] = [:]

    public static func bundleFinder(_ finder: BundleFinder.Type) -> Bundle {
        #if !DEBUG
        return finder.packageModule
        #else

        let bundleName = "\(finder.packageName)_\(finder.moduleName).bundle"

        if let bundle = foundBundles[bundleName] {
            return bundle
        }

        let candidates = [
            // Main app bundle
            Bundle.main.resourceURL,
            
            // Framework bundle location
            Bundle(for: finder.self).resourceURL,
            
            // CLI
            Bundle.main.bundleURL,
            
            // iOS Previews
            Bundle(for: finder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent(),
            
            // macOS Previews
            Bundle(for: finder.self).resourceURL?.deletingLastPathComponent().deletingLastPathComponent().deletingLastPathComponent(),
        ]

        for candidate in candidates {
            let bundlePath = candidate?.appendingPathComponent(bundleName)
            if let bundle = bundlePath.flatMap(Bundle.init(url:)) {
                foundBundles[finder.packageName] = bundle
                return bundle
            }
        }
        fatalError("Unable to find bundle: \(bundleName)")
        #endif
    }
}

////////////////////////////////////
// "Template" in each package module
import Foundation

extension Foundation.Bundle {
    @usableFromInline
    class _CurrentBundleFinder: BundleFinder {
        @usableFromInline
        static let packageName: String = "YourPackageName"

        #if swift(<6.0)
        @usableFromInline
        static let moduleName: String = String(#fileID.split(separator: "/")[0])
        #else
        #error("Module name calculating not yet supported on Swift 6.0+")
        #endif

        @usableFromInline
        static let packageModule: Bundle = .module
    }

    /// Use this instead of `.module` for finding resources.
    @usableFromInline
    internal static var package: Bundle { .bundleFinder(_CurrentBundleFinder.self) }
}