How swift-section Extracts Private iOS Swift Interfaces from Mach‑O Binaries

iOS system frameworks hide their internal structures, but a new tool called swift-section can read Swift interface definitions directly from Mach‑O binaries, allowing analysts to inspect Apple’s private frameworks without source code.

Using a single command, the tool extracts the interface:

./swift-section/Products/swift-section interface \
  --output-path AlarmKit.swift \
  /path/to/AlarmKit.framework/AlarmKit

After execution, a standard Swift file is produced containing all internal Swift types, protocols, and conformance relationships of the target framework.

Technical principle

The operation relies on the strict layout of Swift ABI objects. For example, the ProtocolDescriptor follows a fixed binary format. swift-section leverages this by:

Reading __swift5_* metadata sections : Mach‑O binaries contain sections prefixed with __swift5_ that store Swift type metadata.

Parsing ABI‑defined structures : According to the Swift ABI specification, the tool decodes the descriptors to reconstruct types, protocols, and their relationships.

Demangling symbol names : A custom demangler translates the compiled symbol names back into readable Swift code.

What can be seen?

Applying swift-section to Apple’s private DesignLibrary framework revealed the original interface of the “Liquid Glass” configuration, exposing details that were never publicly documented.

Important clarification

swift-section is not a decompiler; it cannot reconstruct actual source‑code logic. It only rebuilds interface definitions from binary type metadata, which is nevertheless sufficient for security researchers and developers to understand framework architecture, class hierarchies, and public APIs.

Conclusion

By exploiting the standardized Swift ABI, swift-section provides a new key for iOS security analysis, exposing the inner workings of closed‑source frameworks without touching source code. It is a noteworthy addition for security analysts, framework developers, and anyone interested in iOS internals.