> For the complete documentation index, see [llms.txt](https://docs.caf.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.caf.io/caf-sdk/ios/standalone-modules/caffaceliveness/builder.md).

# Building the SDK

## Creating a Liveness SDK instance

In order to create an instance of `CafFaceLivenessSDK`, we need to use our `CafFaceLivenessBuilder`. This allows you to configure all necessary configurations.

### Builder Methods

| Parameter                           | Required | Description                                                                                   |
| ----------------------------------- | -------- | --------------------------------------------------------------------------------------------- |
| `setStage(CAFStage)`                | No       | Defines the environment stage (e.g., `.prod`, `.beta`). Default is `.prod`.                   |
| `setImageUrlExpirationTime(String)` | No       | Sets the expiration time for the image URL used in the scan capture. Default is `"3H"`.       |
| `setLoadingScreen(Bool)`            | No       | Enables or disables the default loading screen during SDK loading events. Default is `false`. |
| `delegate = self`                   | Yes      | Sets the delegate to handle liveness verification events.                                     |

### Example

```swift
    private var sdk: CafFaceLivenessSDK?

private func setupCafFaceLiveness() {
    sdk = CafFaceLivenessSDK.CafFaceLivenessBuilder()
        .setStage(.prod)
        .setImageUrlExpirationTime("2H")
        .setLoadingScreen(withLoading: true)
        .build()
    
    sdk?.delegate = self
    sdk?.startSDK(viewController: self, mobileToken: "your_mobile_token", personId: "your_person_id")
}

// MARK: - CafFaceLivenessDelegate

extension YourViewController: CafFaceLivenessDelegate {
    func didFinishWithSuccess(livenessResult: CafLivenessResult) {
        print("Success: \(livenessResult.signedResponse ?? "No response")")
    }

    func cancelled() {
        print("Liveness detection cancelled")
    }

    func didFinishWithError(sdkFailure: CafSDKFailure) {
        print("Error: \(sdkFailure.description ?? "Unknown error")")
    }

    func loading() {
        print("Liveness detection loading")
    }

    func loaded() {
        print("Liveness detection loaded")
    }
}
```


---

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