# `GSInstance.id`

*Instance Property*

A unique identifier for the instance that does not change when other properties such as the same are changed.

## Declaration

```swift
var id: String { get set }
```

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

```python
id() -> str
setId_(id: str)
```

## Discussion

This identifier is written starting from Glyphs file format version 4.