# `GSLayer.associatedMasterId`

*Instance Property*

The identifier of the font master that supplies metrics and other master-specific values.

## Declaration

```swift
var associatedMasterId: String? { get set }
```

```objc
@property (nonatomic, strong) NSString * associatedMasterId;
```

[See also `associatedMasterId` in the Python API](https://docu.glyphsapp.com/#GSLayer.associatedMasterId)

```python
pyobjc_instanceMethods.associatedMasterId() -> str
pyobjc_instanceMethods.setAssociatedMasterId_(associatedMasterId: str)
```

## Discussion

For a master layer, this is the same as [`GSLayer.layerId`](/Core/GlyphsCore/GSLayer/layerId).

## See Also

### Associated Master

- [`GSLayer associatedFontMaster`](/Core/GlyphsCore/GSLayer/associatedFontMaster) — The master that supplies master-specific values for the layer.
- [`GSLayer associatedFontMasterThin:`](/Core/GlyphsCore/GSLayer/associatedFontMasterThin:) — Resolves the associated master with control over the amount of interpolated master data.
- [`GSLayer associatedFontMasterFast`](/Core/GlyphsCore/GSLayer/associatedFontMasterFast) — Directly looks up the associated master by its identifier.