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# init(screenSize:layer:label:)

A convenience initializer that creates a rate map descriptor with a single rate layer.

```
convenience init(screenSize: MTLSize, layer: MTLRasterizationRateLayerDescriptor, label: String? = nil)
```

## Parameters

`screenSize`

The logical size, in pixels, of the viewport coordinate system.

`layer`

A descriptor for the rate layer to create.

`label`

A string that identifies the resulting rate map.

## Return Value

A descriptor object whose [`screenSize`](/documentation/Metal/MTLRasterizationRateMapDescriptor/screenSize) and [`label`](/documentation/Metal/MTLRasterizationRateMapDescriptor/label) properties are set to the provided values. Layer `0` in the rate map is set to the provided layer descriptor.

---

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