perf(ios): ship default metadata as a separate framework for embedding hosts only - #488
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…amework The framework already embeds metadata-arm64.bin as its __DATA,__TNSMetadata section, which is the only copy the runtime reads. The loose 8.8 MB resource copy is never read, and the opt-in "Add default metadata" phase copied from a NativeScript/metadata/ directory that does not exist, gated on an INCLUDE_DEFAULT_METADATA setting nothing sets.
…ter is given When Config.MetadataPtr is nil, look for a non-empty __DATA,__TNSMetadata section in the host executable (or its <executable>.debug.dylib in Xcode debug-dylib builds) before falling back to the metadata embedded in NativeScript.framework. Hosts set up by 'ns embed ios' link their own metadata this way but never pass the pointer, so they were silently running on the framework's 2024 snapshot.
…ramework NativeScript.framework no longer embeds the 8.8 MB default metadata snapshot. It now lives in a separate NativeScriptDefaultMetadata framework (iOS, simulator and Mac Catalyst) that only the NativeScriptSDK SwiftPM product links, so apps built by the NativeScript CLI, which use the NativeScript product and link their own metadata, stop shipping it. When neither Config.MetadataPtr nor a host executable section is available, the runtime loads the accessor exported by NativeScriptDefaultMetadata.framework (already loaded, or found next to NativeScript.framework), and otherwise fails to start with an actionable message instead of running on metadata the host never asked for. build_default_metadata.sh builds the xcframework, build_spm_artifacts.sh packages it with an NS_CHECKSUM_DEFAULTMETADATA_IOS checksum, and generate-spm-manifest.mjs declares it as a binary target of the NativeScriptSDK product. visionOS has no default metadata build.
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📝 WalkthroughWalkthroughThe iOS products now include a separate default metadata framework. NativeScript resolves metadata from configuration, the host executable or matching debug dylib, and then the framework. Build scripts create the framework XCFramework, and the generated Swift Package manifest includes it in NativeScriptSDK. ChangesiOS Metadata Framework and Distribution
Priority: ➖ Normal Estimated code review effort: 4 (Complex) | ~45 minutes Change: Feature Sequence Diagram(s)sequenceDiagram
participant NativeScript
participant Config
participant HostImages
participant MetadataFramework
NativeScript->>Config: Read MetadataPtr
NativeScript->>HostImages: Scan executable and matching debug dylib
HostImages-->>NativeScript: Return nonempty metadata section or no section
NativeScript->>MetadataFramework: Resolve framework accessor if host metadata is absent
MetadataFramework-->>NativeScript: Return metadata pointer if available
Suggested reviewers: Merge Risk: 🔵 Low · up to The new metadata build script works in the default macOS environment. Two small script issues remain. A numeric setting such as Security Architecture ReviewSecurity architecture risk: 🔵 Low · up to The new fallback remains within the application's native-code trust boundary; no independently reachable script or network attack path was established. The main concern is failure recovery: missing metadata can reject initialization after shared application paths have changed. Deployed framework loading and signing behavior remain unverified. Retained concerns
Security review detailsSecurity Blast Radius
Security Findings and Attack Paths
Trust Boundaries and Controls
Resilience and Maintainability Implications
Hardening Proposals
🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 6 files. (5 skipped: 5 unsupported.) ✨ Finishing Touches 💡 1📝 Generate docstrings 💡
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edusperoni
marked this pull request as ready for review
October 5, 2026 17:58
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Review comments at @build_default_metadata.sh:
- Line 8: Update the numeric pattern in to_bool so Bash correctly recognizes
numeric BUILD_CATALYST values, including 1, as boolean inputs instead of taking
the invalid-value branch. Use a Bash-compatible pattern or explicitly handle
zero and nonzero values; preserve the existing behavior for other inputs.
- Line 42: Update the DIST assignment to use the shell’s PWD variable expansion
rather than command substitution, and quote the resulting path so the script
works without a PWD executable.
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⛔ Files ignored due to path filters (1)
NativeScriptDefaultMetadata/metadata-arm64.binis excluded by!**/*.bin
📒 Files selected for processing (12)
NativeScript/NativeScript.mmNativeScriptDefaultMetadata/Info.plistNativeScriptDefaultMetadata/NativeScriptDefaultMetadata.cREADME.mdbuild_all_ios.shbuild_default_metadata.shbuild_nativescript.shbuild_spm_artifacts.shscripts/generate-spm-manifest.mjsspm-templates/local-spm-ios/Package.swiftv8ios.xcodeproj/project.pbxprojv8ios.xcodeproj/xcshareddata/xcschemes/NativeScriptDefaultMetadata.xcscheme
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- build_nativescript.sh
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…k build scripts to_bool matched numbers with the case pattern [0-9]+, which is a glob for one digit followed by a literal plus, so BUILD_CATALYST=1 and friends were treated as invalid and turned the slice off. DIST was computed with $(PWD), which only resolves to /bin/pwd on a case-insensitive filesystem.
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What
NativeScript.frameworkships an 8.8 MB default metadata blob twice, and apps built by the CLI use neither copy. This PR removes both from the runtime framework and moves the default into a small separate framework that only embedding hosts link.Both copies came from #231 (embedding into host projects):
__DATA,__TNSMetadatasection linked into the framework binary — the fallback used whenConfig.MetadataPtris nilCLI apps link their own metadata into the app executable and pass the pointer, so for them this is 17.6 MB of dead weight per app (about 5.4 MB of the compressed download).
Changes
Three commits, each buildable on its own:
INCLUDE_DEFAULT_METADATApassthrough.Config.MetadataPtris nil, the runtime now looks for a non-empty__DATA,__TNSMetadatasection in the host executable (or its<executable>.debug.dylibin Xcode debug-dylib builds). Hosts set up byns embed ioslink their metadata this way but never pass the pointer, so until now they ran on the framework's default snapshot.NativeScriptDefaultMetadata.framework. New framework target (iOS, simulator, Mac Catalyst) carrying the blob and exporting an accessor.build_default_metadata.shbuilds it,build_spm_artifacts.shpackages it, andgenerate-spm-manifest.mjsadds it as a third binary target.Resolution order at startup:
Config.MetadataPtr→ host executable section →NativeScriptDefaultMetadata.framework(already loaded, or next toNativeScript.framework) → fail with an actionable message.SwiftPM products after this PR:
NativeScriptNativeScriptSDKSize
NativeScriptbinary, Release device build (same command)metadata-arm64.binin the frameworkbuild_nativescript.sh)Artifact zips from a full local build:
NativeScript.xcframework.zip59.9 MB,NativeScriptDefaultMetadata.xcframework.zip11.2 MB,TKLiveSync.xcframework.zip1.2 MB.Behaviour changes
NativeScriptSDKwith no metadata of their own (the documented zero-config embedding path, including purerunScriptStringuse): unchanged, the default now comes from the extra framework.__TNSMetadatasection but pass no pointer (e.g.ns embed ios): now use their own metadata instead of the default snapshot.NativeScriptproduct with no metadata anywhere: previously ran silently on the default; now fail at startup with a message naming the three ways to provide metadata.Open questions
NativeScriptVisionOSis the single product CLI apps use, and the default blob is iOS SDK metadata, so I left it lean. Zero-config embedding on visionOS would now hit the startup error. Is anyone relying on that?ios-spmREADME currently says only linked artifacts are downloaded.ios-spmREADME needs its products table updated once this ships; that repo is not touched here.Testing
MetadataPtr(host-section path): 1734 tests, 0 failures.NativeScriptDefaultMetadata.frameworkin the app'sFrameworks/the runtime boots on the default metadata; without it the fatal message is logged.build_all_ios.shpipeline steps run locally throughbuild_spm_artifacts.sh ios; the generated manifest parses withswift package dump-package.Not verified: a real SwiftPM host linking
NativeScriptSDK(device or Catalyst), and the already-loaded lookup path (dlsym(RTLD_DEFAULT)); the smoke test exercised the sibling-frameworkdlopenpath only.Summary by CodeRabbit
NativeScriptSDKoption that includes default iOS metadata for apps that don’t provide their own.