> 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/caffaceauth/start-sdk.md).

# Start the SDK

### Instantiating the SDK

First, instantiate an object of type `CafFaceAuthSDK`. This object is for you to configure all your business rules:

```swift
class CafFaceAuthViewController: UIViewController {
    var faceAuthenticator: FaceAuthSDK?

    func setupFaceAuthenticator() {
        faceAuthenticator = FaceAuthSDK.Builder()
        // the table below shows all the SDK configuration options
        .build()
        faceAuthenticator?.delegate = self
    }

    func startFaceAuthenticator() {
        faceAuthenticator?.startFaceAuthSDK(viewController: self, mobileToken:"yourMobileToken", personId: "personId")
    }
}
```

### Getting the Results

You must implement the `FaceAuthSDKDelegate` class to get the SDK results. To do that, you should provide a `UIViewController` to your SDK instance:

```swift
faceAuthenticator?.delegate = self
```

#### Delegate Implementation

The delegate below must be implemented to handle the SDK results. When implementing the delegate extension, you will have access to an object depending on the return type. In each case, the object carries different information.

```swift
extension FaceAuthViewController: FaceAuthSDKDelegate {
  func didFinishSuccess(with faceAuthenticatorResult: CafFaceAuth.FaceAuthenticatorResult) {
    //handle success result
  }
    
  func didFinishWithError(with faceAuthenticatorErrorResult: CafFaceAuth.FaceAuthenticatorErrorResult) {
    //handle error result
  }
    
  func didFinishFaceAuthWithCancelled() {
    //handle when user closes the SDK
  }
    
  func openLoadingScreenStartSDK() {
    //handle loading screen - display
  }
    
  func closeLoadingScreenStartSDK() {
    //handle loading screen - dismiss
  }
    
  func openLoadingScreenValidation() {
    //handle loading screen - display
  }
    
  func closeLoadingScreenValidation() {
    //handle loading screen - dismiss
  }
}   
```

#### Loading Screen

To create a loading screen during the SDK validation processes, you need to implement a view with the loading screen and display it in the *open* and *close* delegate functions. `openLoadingScreenStartSDK()`, `closeLoadingScreenStartSDK()`, `openLoadingScreenValidation()`, `closeLoadingScreenValidation()`

In the SDK implementation, it is necessary to add the view to the view stack using the following code. This makes the view visible.

```swift
view.addSubview(loadingHUD)
```

This view should be added before the Builder of the SDK.


---

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