glyphs-objc-headers

name	glyphs-objc-headers
description	Searches GlyphsCore Objective-C header files (174 headers) for class APIs, protocol methods, properties, enums, and constants. Use when looking up GSFont/GSLayer/GSGlyph properties, finding GlyphsReporter or GlyphsFilter protocol methods, or searching Obj-C type definitions for plugin development.

GlyphsCore Obj-C Headers Skill

Query 174 Objective-C header files from the GlyphsCore framework to find class APIs, protocol methods, properties, enums, and constants. This skill is the authoritative surface for the Objective-C side of the Glyphs API — Python wrappers ultimately bridge through these declarations.

Headers Path

${GLYPHS_APP_HEADERS_PATH:-/Applications/Glyphs 3.app/Contents/Frameworks/GlyphsCore.framework/Versions/A/Headers}

If the env var is not set, use the default path above. The path resolves to the installed Glyphs 3 application bundle; the skill works without a separate GlyphsSDK checkout for this domain.

When to use this skill versus the Python skill

Question	Use
"What properties does GSFont expose in Python?"	glyphs-python-api
"What's the Obj-C selector for GSFont.familyName?"	This skill
"What protocol methods can a Filter plugin implement?"	This skill (GlyphsFilterProtocol.h)
"What does _LightTableInterface look like at runtime?"	This skill + glyphs-light-table (cross-ref)
"What enum cases exist for GSFontMaster axes?"	This skill (header typedef enum)

Quick Start Patterns

# Find a class definition
Grep "@interface GSFont" path/to/Headers/

# Find all properties of a class
Grep "@property" path/to/Headers/GSFont.h

# Find a protocol and its methods
Read path/to/Headers/GlyphsReporterProtocol.h

# Search for an enum or constant
Grep "typedef.*enum" path/to/Headers/ --glob "*.h"

# Find which header declares a method
Grep "drawForegroundForLayer" path/to/Headers/

Protocol Files

Glyphs plugin protocols follow a consistent naming convention:

Pattern	Example
Glyphs*Protocol.h	GlyphsReporterProtocol.h, GlyphsFilterProtocol.h
GS*Protocol.h	GSAppDelegateProtocol.h, GSContentProtocol.h

To list all protocols:

Glob path/to/Headers/*Protocol*.h

Advanced Search

# Find subclass relationships
Grep "@interface GS\\w+ : " path/to/Headers/

# Find all extern constants
Grep "^extern" path/to/Headers/

# Find category extensions for a class (e.g., GSLayer+*)
Glob path/to/Headers/GSLayer+*.h

# Find delegate/notification patterns
Grep "Notification\|Delegate" path/to/Headers/

Worked workflow — "Find every protocol method a Reporter plugin can implement"

# 1. Locate the protocol file
Read path/to/Headers/GlyphsReporterProtocol.h

# 2. Filter for @optional vs @required sections
Grep -n "@optional\|@required\|^- " path/to/Headers/GlyphsReporterProtocol.h

# 3. Cross-check with the SDK skill's method classification
#    (glyphs-sdk-reference will categorize protocol/python_helper/python_wrapped)

This is the canonical pattern for plugin development: header for the contract, then SDK skill for the Python lifecycle wrapper.

Worked workflow — "What's the Obj-C type behind GSLayer.paths?"

# 1. Find the @property declaration
Grep "@property.*paths" path/to/Headers/GSLayer.h

# 2. If the property type is NSArray<X>, find the element type
Grep "@interface GSPath" path/to/Headers/

# 3. Check category extensions for additional methods on the array
Glob path/to/Headers/GSLayer+Path*.h

The header tells you the actual class names and method signatures the Python wrapper hides.

Glyphs-Specific Notes

Conditional Compilation Guards

About 26 headers contain #ifndef GLYPHS_LITE or #ifndef LIBCORE guards. Code inside these guards is only available in the full Glyphs 3, not in Glyphs Mini or the core library.

# Find guarded sections in a header
Grep "GLYPHS_LITE\|LIBCORE" path/to/Headers/GSFont.h

When reading a header with these guards, note which APIs are full-version only. This is the most common source of "the Python wrapper has this attribute but I can't find it in the header" confusion.

Class Categories (Extensions)

Many core classes have functionality split across multiple headers:

• GSFont.h + GSFont+GenerateGlyphs.h + GSFont+SerialImport.h + GSFont+SerialSave.h
• GSLayer.h + GSLayer+PathOperations.h + GSLayer+Autohinting.h + ...
• GSGlyph.h + GSGlyph+MetricsKeys.h + GSGlyph+TrueTypeCurves.h

Always check for ClassName+*.h extensions when querying a class API. A missing method in the main header is almost always in a category file.

Selector ↔ Python method mapping

Glyphs' Python bridge follows PyObjC conventions:

Obj-C selector	Python method
nameForKey:	nameForKey_("X")
font:loadFromPath:options:	font_loadFromPath_options_(f, p, o)
setLayer:forKey:	setLayer_forKey_(layer, key)

Each : becomes _. Trailing colon stays. For zero-argument selectors (init, mainFont), no underscore is added.

Third-party Plugin APIs (Runtime Only)

Some third-party plugins expose Objective-C classes accessible via runtime introspection (NSClassFromString, objc_getClass), even without header files.

• Light Table (Git version control): Exposes LightTableInterface, LightTableSignature, LightTableCommit, LightTableRecord, LightTableVersion, LightTableRestorationInfo. See the glyphs-light-table skill for selector mappings and usage.

Common edge cases

• Header path missing → confirm Glyphs 3 is installed at /Applications/Glyphs 3.app; for a non-standard install set GLYPHS_APP_HEADERS_PATH.
• Property appears in Python but not in .h → check category headers (ClassName+*.h) and GLYPHS_LITE guards before concluding it's runtime-only.
• Method has no matching protocol → it may be on a private subclass (no Protocol.h declaration). Search the class header directly.
• Multiple @interface blocks for one class → categories add to the base class; merge all matches before answering.

Cross-skill collaboration

Question	Use this skill	Use instead	Reason
"What Obj-C properties does GSFont have?"	✅	—	This is the headers' job
"What Python attributes does GSFont have?"	—	glyphs-python-api	Wrapper surface differs
"What's the plugin lifecycle protocol signature?"	✅	—	Headers define the contract
"How do I implement a Reporter plugin?"	—	glyphs-sdk-reference	Lifecycle + template
"What's the runtime class of _LightTableInterface?"	partial	glyphs-light-table	Third-party plugin surface
"What's a GSFormatVersion3 value?"	—	glyphs-python-api (constants)	Constant lookups are easier in Python skill

Reference

See references/header-categories.md for a categorized guide to the 174 headers.