rive_native Package.swift fails to compile under Swift Package Manager: `String.replacingOccurrences` without `import Foundation`

Affected versions

Confirmed in rive_native 0.1.4 and 0.1.6 (likely all SPM-shipping versions). Pulled transitively via rive 0.14.4 / 0.14.6.

Environment

• Flutter 3.41.4 (stable)
• Xcode 26.0.1 (build 17A400)
• macOS 14, arm64
• Swift 6.2 (swiftlang-6.2.0.19.9 clang-1700.3.19.1)
• iOS deployment target 15.0
• Hybrid Flutter SPM mode (flutter.config.enable-swift-package-manager: true in pubspec.yaml)

Bug

rive_native/ios/rive_native/Package.swift lines 1–6:

// swift-tools-version: 5.9
import PackageDescription

// Version and checksum are auto-updated by native/build_xcframework.sh
let riveNativeVersion = "0.1.6+1"
let riveNativeVersionURLComponent = riveNativeVersion.replacingOccurrences(of: "+", with: "%2B")

String.replacingOccurrences(of:with:) is a Foundation API. Swift Package Manager compiles Package.swift manifests in a minimal toolchain that does not auto-import Foundation. Result: every swift package resolve / xcodebuild -resolvePackageDependencies against a Flutter project that pulls in rive_native fails with:

error: Invalid manifest (compiled with: ["…", ".../rive_native/Package.swift", …])
.../rive_native/Package.swift:6:55: error: value of type 'String' has no member 'replacingOccurrences'
 4 | // Version and checksum are auto-updated by native/build_xcframework.sh
 5 | let riveNativeVersion = "0.1.6+1"
 6 | let riveNativeVersionURLComponent = riveNativeVersion.replacingOccurrences(of: "+", with: "%2B")
   |                                                       `- error: value of type 'String' has no member 'replacingOccurrences'

Cascading symptom (why this is hard to diagnose)

When SPM fails to compile a single plugin manifest in a Flutter FlutterGeneratedPluginSwiftPackage, the resolver bails out before walking transitive deps. The high-level error xcodebuild reports is misleading — in our case it surfaced as a fake firebase-ios-sdk version conflict:

xcodebuild: error: Could not resolve package dependencies:
  Failed to resolve dependencies Dependencies could not be resolved because
  'cloud_functions' depends on 'firebase-ios-sdk' 12.9.0..<13.0.0 and
  root depends on 'firebase-ios-sdk' 11.7.0..<12.0.0.

The 11.7.0 pin doesn't exist anywhere in the project — it's an artifact of SPM falling back to stale resolution state when the manifest compile fails. We spent ~2 hours chasing the firebase-ios-sdk red herring before tracing the actual rive_native manifest error in swift package resolve --verbose output.

Fix (one line)

Add import Foundation to rive_native/ios/rive_native/Package.swift line 2:

// swift-tools-version: 5.9
import PackageDescription
import Foundation  // ← add this

// Version and checksum are auto-updated by native/build_xcframework.sh
let riveNativeVersion = "0.1.6+1"
let riveNativeVersionURLComponent = riveNativeVersion.replacingOccurrences(of: "+", with: "%2B")

Verified locally: with import Foundation added to the pub-cache copy, xcodebuild -resolvePackageDependencies proceeds past manifest compilation and resolves the full graph successfully.

This is the same pattern other Flutter plugins use — e.g. firebase_core/ios/firebase_core/Package.swift imports both PackageDescription and Foundation since it uses String(contentsOfFile:) and NSString.path(withComponents:).

Why this matters now

Flutter 3.41+ ships SPM as a project-local opt-in (flutter.config.enable-swift-package-manager: true). With the Firebase Apple SDK CocoaPods publishing cutoff in October 2026, every Flutter+Firebase iOS app needs to migrate to SPM mode by then — and any project that pulls rive (which transitively pulls rive_native) will hit this error during their migration.

Happy to send a PR if rive-app accepts external contributions for rive_native — just let me know.

Start with rive_native/ios/rive_native/Package.swift and inspect the manifest imports and String.replacingOccurrences call. Run swift package resolve or xcodebuild -resolvePackageDependencies against a project using rive_native. Done means the manifest compiles and package dependency resolution proceeds without the reported error.