Android Webview

To allow Android Webview to visit camera, you need to override the onPermissionRequest method in your app:

private var mWebChromeClient: WebChromeClient = object : WebChromeClient() {

    override fun onPermissionRequest(request: PermissionRequest?) {

        //  IMPORTANT: Check host and adapt filter to allow camera access
        // e.g. if (request?.origin?.host == "xxx") {...}

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            if (context is BaseActivity) {
                if (ContextCompat.checkSelfPermission(
                        context,
                        Manifest.permission.CAMERA
                    ) == PackageManager.PERMISSION_GRANTED
                ) {
                    request?.grant(request.resources)
                } else {
                    context.requestPermission(Manifest.permission.CAMERA) { granted ->
                        if (granted) {
                            request?.grant(request.resources)
                        } else {
                            request?.deny()
                        }
                    }
                }
            }
        }
    }
}

iOS Webview

To enable iOS Webview camera permission, you need the following adjustment:

Inside info.plist file, set NSCameraUsageDescription to allow the app to access camera.

<key>NSCameraUsageDescription</key> 
<string>$(PRODUCT_NAME) need to use your rear camera</string>

Config Webview instance to allow inline media playback, disable user action for playback, enable JavaScript, and enable JavaScript to automatically open windows.

let configuration = WKWebViewConfiguration()
configuration.allowsInlineMediaPlayback = true
configuration.mediaTypesRequiringUserActionForPlayback = []
configuration.preferences.javaScriptEnabled = true
configuration.preferences.javaScriptCanOpenWindowsAutomatically = true
self.webView = WKWebView(frame: self.view.bounds, configuration: configuration)

Before entering H5 Verfication Page, check and request for camera access first.

// 请求相机权限(swift 样例代码)
// Request camera permission (in Swift)
func checkAVAuthorizationStatus(with block: @escaping((_ authed: Bool) -> Void)) {
    let authStatus = AVCaptureDevice.authorizationStatus(for: .video)
    if authStatus == .authorized {
        block(true)
    } else if authStatus == .denied || authStatus == .restricted {
        block(false)
    } else {
        AVCaptureDevice.requestAccess(for: .video) { (result) in
            DispatchQueue.main.async {
                block(result)
            }
        }
    }
}

// Usage
// Check auth status before entering H5 webpage.
self.checkAVAuthorizationStatus { authed in
  if authed {
    // Enter H5 webpage directly
  } else {
    // Logic to handle camera unauthorised.
  }
}

(Optional) To avoid camera permission prompt in H5 every time.

// Make sure your ViewController inherits WKUIDelegate.
class ViewController: UIViewController, WKUIDelegate {
    ...

    // Only verified for iOS 15+
    @available(iOS 15.0, *)
    func webView(_ webView: WKWebView, requestMediaCapturePermissionFor origin: WKSecurityOrigin, initiatedByFrame frame: WKFrameInfo, type: WKMediaCaptureType, decisionHandler: @escaping (WKPermissionDecision) -> Void) {
        // NOTE: please add necessary security check like domain filter if needed.
        decisionHandler(.grant)
    }
}

self.webView.uiDelegate = self