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Custom capture UI

Use MBCaptureSessionView when your application must own the surrounding controls and layout. The SDK still manages camera capture and validation; your view controller manages presentation and user interaction.

Unlike MBCaptureSessionViewController, the custom view does not present the camera-permission flow for you. Request video access before creating and starting MBCaptureSessionView:

AVCaptureDevice.requestAccess(for: .video) { [weak self] granted in
    DispatchQueue.main.async {
        if granted {
            self?.installAndStartCaptureView()
        } else {
            self?.showCameraPermissionMessage()
        }
    }
}

Import AVFoundation and include NSCameraUsageDescription in the application’s Info.plist.

Create and attach the capture view​

import UIKit
import AVFoundation
import MobaiBiometric

final class CustomCaptureViewController: UIViewController {
    private var captureView: MBCaptureSessionView!

    func installAndStartCaptureView() {
        captureView = MBCaptureSessionView(
            options: MBCaptureSessionOptions(
                videoCaptureDuration: 2_000,
                captureConstraints: .v3,
                imageQualityLevel: .level2
            )
        )

        captureView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(captureView)

        NSLayoutConstraint.activate([
            captureView.topAnchor.constraint(equalTo: view.topAnchor),
            captureView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            captureView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            captureView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])

        captureView.captureSessionDelegate = self
        captureView.boundingBoxFaceValidatorDelegate = self
        captureView.countDownDelegate = self
        captureView.progressDelegate = self
        captureView.onStartCapturing(sessionId: sessionId)
    }

    override func viewWillDisappear(_ animated: Bool) {
        captureView?.onStopCapturing()
        super.viewWillDisappear(animated)
    }
}

Calling onStopCapturing() when the screen disappears prevents the camera from continuing when the screen is no longer visible. Call onStartCapturing(sessionId:) again before reusing the same view.

Handle session events​

extension CustomCaptureViewController: MBCaptureSessionDelegate {
    func onSuccess(result: MBCaptureSessionResult) {
        upload(result)
    }

    func onFailure(error: MBCaptureSessionError) {
        showRetry(for: error)
    }

    func onStateChanged(captureState: MBCaptureState) { }
}

Show V3 feedback​

V2 and V3 use MBBoundingBoxFaceValidatorDelegate:

extension CustomCaptureViewController: MBBoundingBoxFaceValidatorDelegate {
    func onValidating(
        _ faceStatus: Result<MBFaceGeometryModel, MBFaceBoundingBoxStatus>
    ) {
        switch faceStatus {
        case .success:
            feedbackLabel.text = "Hold still"

        case .failure(let status):
            feedbackLabel.text = feedbackText(for: status)
        }
    }
}

Check geometry before lighting so the user receives one clear instruction at a time. See Capture constraints and image quality for the status fields.

Show progress and countdown​

extension CustomCaptureViewController: MBCaptureProgressDelegate, MBCountDownDelegate {
    func onCaptureProgress(captureProgressCounter: Float) {
        progressView.progress = captureProgressCounter
    }

    func onCountDown(timeCounter: Int) {
        countdownLabel.text = String(timeCounter)
    }
}

Manual capture​

Set autoCaptureEnabled to false, then call takePicture() from your button after the SDK reports a valid face:

@IBAction private func captureButtonTapped() {
    captureView.takePicture()
}

Disable the button until validation succeeds to avoid collecting an invalid capture.