# `GSFont mutableClasses`

*Instance Method*

A mutable array of layout classes.

## Declaration

```swift
func mutableClasses() -> NSMutableArray
```

```objc
- (NSMutableArray<GSClass *> *) mutableClasses;
```

```python
mutableClasses() -> list[GSClass]
```

## Discussion

Prefer the collection mutation methods when ownership, undo, and notifications matter.

## See Also

### Layout Classes

- [`GSFont.classes`](/Core/GlyphsCore/GSFont/classes) — Layout classes in the font.
- [`GSFont countOfClasses`](/Core/GlyphsCore/GSFont/countOfClasses) — The number of layout classes.
- [`GSFont objectInClassesAtIndex:`](/Core/GlyphsCore/GSFont/objectInClassesAtIndex:) — The layout class at an index.
- [`GSFont indexOfObjectInClasses:`](/Core/GlyphsCore/GSFont/indexOfObjectInClasses:) — The index of a layout class, or `NSNotFound` when the class is not in the font.
- [`GSFont classForTag:`](/Core/GlyphsCore/GSFont/classForTag:) — The layout class with the specified name.
- [`GSFont addClass:`](/Core/GlyphsCore/GSFont/addClass:) — Adds a layout class.
- [`GSFont addClassFromCode:`](/Core/GlyphsCore/GSFont/addClassFromCode:) — Adds a layout class parsed from FEA class code.
- [`GSFont insertObject:inClassesAtIndex:`](/Core/GlyphsCore/GSFont/insertObject:inClassesAtIndex:) — Inserts a layout class at an index.
- [`GSFont removeClass:`](/Core/GlyphsCore/GSFont/removeClass:) — Removes a layout class.
- [`GSFont removeObjectFromClassesAtIndex:`](/Core/GlyphsCore/GSFont/removeObjectFromClassesAtIndex:) — Removes the layout class at an index.
- [`GSFont replaceObjectInClassesAtIndex:withObject:`](/Core/GlyphsCore/GSFont/replaceObjectInClassesAtIndex:withObject:) — Replaces the layout class at an index.