# `GSLayer.layerGroupKey`

*Instance Property*

A derived key used to group corresponding special and color layers.

## Declaration

```swift
var layerGroupKey: String? { get }
```

```objc
@property (nonatomic, readonly) NSString * layerGroupKey;
```

```python
layerGroupKey() -> str
```

## Discussion

Layers without grouping attributes can have no group key.

## See Also

### Identity

- [`GSLayer.layerId`](/Core/GlyphsCore/GSLayer/layerId) — The identifier under which the layer is stored in its glyph.
- [`GSLayer.layerKey`](/Core/GlyphsCore/GSLayer/layerKey) — A derived key that distinguishes the layer by its role and attributes.
- [`GSLayer resetLayerKey`](/Core/GlyphsCore/GSLayer/resetLayerKey) — Invalidates the derived layer key after information used to form it changes.