# `GSLayer userDataForKey:`

*Instance Method*

The user-data value for a key, or `nil` if no value is set.

## Declaration

```swift
func userData(forKey key: String) -> NSObject?
```

```objc
- (NSObject *) userDataForKey:(NSString *) key;
```

```python
userDataForKey_(key: str) -> NSObject
```

## See Also

### User Data

- [`GSLayer.userData`](/Core/GlyphsCore/GSLayer/userData) — Persistent values associated with the layer by API clients.
- [`GSLayer setUserData:forKey:`](/Core/GlyphsCore/GSLayer/setUserData:forKey:) — Sets or removes a persistent user-data value.
- [`GSLayer removeUserDataForKey:`](/Core/GlyphsCore/GSLayer/removeUserDataForKey:) — Removes a user-data value.