> ## Documentation Index
> Fetch the complete documentation index at: https://liquidai-alay2shah-sync-notebook-snippets.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Advanced Features

> API reference for constrained generation and function calling in the LEAP iOS SDK

## `GenerationOptions`

Tune generation behavior with `GenerationOptions`.

```swift theme={"theme":{"light":"github-light","dark":"github-dark"}}
public struct GenerationOptions {
  public var temperature: Float?
  public var topP: Float?
  public var minP: Float?
  public var repetitionPenalty: Float?
  public var jsonSchemaConstraint: String?
  public var functionCallParser: LeapFunctionCallParserProtocol?

  public init(
    temperature: Float? = nil,
    topP: Float? = nil,
    minP: Float? = nil,
    repetitionPenalty: Float? = nil,
    jsonSchemaConstraint: String? = nil,
    functionCallParser: LeapFunctionCallParserProtocol? = LFMFunctionCallParser()
  )
}
```

* Leave a field as `nil` to fall back to the defaults packaged with the model bundle.
* `functionCallParser` controls how tool-call tokens are parsed. `LFMFunctionCallParser` (the default) handles Liquid Foundation Model Pythonic function calling. Supply `HermesFunctionCallParser()` for Hermes/Qwen3 formats, or set the parser to `nil` to receive raw tool-call text in `MessageResponse.chunk`.
* `jsonSchemaConstraint` activates constrained generation. Use `setResponseFormat(type:)` to populate it from a type annotated with the `@Generatable` macro.

```swift theme={"theme":{"light":"github-light","dark":"github-dark"}}
extension GenerationOptions {
  public mutating func setResponseFormat<T: GeneratableType>(type: T.Type) throws {
    self.jsonSchemaConstraint = try JSONSchemaGenerator.getJSONSchema(for: type)
  }
}
```

```swift theme={"theme":{"light":"github-light","dark":"github-dark"}}
var options = GenerationOptions(temperature: 0.6, topP: 0.9)
try options.setResponseFormat(type: CityFact.self)

for try await response in conversation.generateResponse(
  message: user,
  generationOptions: options
) {
  // Handle structured output
}
```

`LiquidInferenceEngineRunner` exposes advanced utilities such as `getPromptTokensSize(messages:addBosToken:)` for applications that need to budget tokens ahead of time. These methods are backend-specific and may be elevated to the `ModelRunner` protocol in a future release.

## Function Calling Types

```swift theme={"theme":{"light":"github-light","dark":"github-dark"}}
public struct LeapFunction {
  public let name: String
  public let description: String
  public let parameters: [LeapFunctionParameter]
}

public struct LeapFunctionParameter {
  public let name: String
  public let type: LeapFunctionParameterType
  public let description: String
  public let optional: Bool
}

public indirect enum LeapFunctionParameterType: Codable, Equatable {
  case string(StringType)
  case number(NumberType)
  case integer(IntegerType)
  case boolean(BooleanType)
  case array(ArrayType)
  case object(ObjectType)
  case null(NullType)
}
```

The parameter type wrappers (`StringType`, `NumberType`, etc.) let you attach descriptions and enumerations so that JSON schemas accurately describe your tools. See the [Function Calling](./function-calling) guide for in-depth usage patterns.