# `GSFont interpolateFontMaster:scale:thin:error:`

*Instance Method*

Interpolates a master for an instance.

## Declaration

```swift
func interpolateFontMaster(_ instance: GSInstance, scale: CGFloat, thin: Bool) throws -> GSFontMaster
```

```objc
- (GSFontMaster *) interpolateFontMaster:(GSInstance *) instance scale:(CGFloat) scale thin:(BOOL) thin error:(NSError **) error;
```

```python
interpolateFontMaster_scale_thin_error_(instance: GSInstance, scale: float, thin: bool) -> tuple[GSFontMaster, NSError]
```

## Parameters

- `scale` — The scale applied to interpolated metrics and outlines.
- `thin` — Pass `YES` when generating a lightweight preview master.
- `error` — On output, a pointer to an error object that describes why the method failed, or `nil` if no error occurred. If you are not interested in the error information, pass `nil` for this parameter.

## Return Value

The interpolated master, or `nil` when interpolation fails.

## Discussion

The returned master contains interpolated master data for the instance location.