# `GSFontMaster setUserData:forKey:`

*Instance Method*

Adds something to the fonts userData.

## Declaration

```swift
func setUserData(_ value: Any?, forKey key: String)
```

```objc
- (void) setUserData:(id) value forKey:(NSString *) key;
```

```python
setUserData_forKey_(value: object, key: str)
```

## Parameters

- `value` — The object should be able to serialize to a plist. If they are not, they should return all infos to store in description (as String).
- `key` — Please use an unique key that gives some indication who put it there (e.g. prefix it with your name or project).

## Discussion

This also triggers undo/document dirty state.