---
title: functionConstantsDictionary
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtlfunction/functionconstantsdictionary
---

# functionConstantsDictionary

A dictionary of function constants for a specialized function.

## Declaration

```swift
var functionConstantsDictionary: [String : MTLFunctionConstant] { get }
```

## Discussion

Discussion This property returns a dictionary of the function constants that you need to provide to specialize this function. This property returns an empty dictionary if this function is already specialized or doesn’t declare any function constants. To create the specialized function, set these constant values in a new MTLFunctionConstantValues object and call the makeFunction(name:constantValues:completionHandler:) method.