import UIKit
import WebKit

class ViewController: UIViewController, WKNavigationDelegate {
     
    var webView: WKWebView!
    var dialogMessage: UIAlertController!
     
    override func loadView() {
        webView = WKWebView()
        webView.navigationDelegate = self
        view = webView
        dialogMessage = UIAlertController(
            title: "Ошибка",
            message: "Приложение данного банка у вас не установлено.",
            preferredStyle: .alert
        )
        dialogMessage.addAction(UIAlertAction(title: "Ок", style: .default, handler: nil))
    }

    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction,
                decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        if (navigationAction.navigationType == .linkActivated) {
            if let url = navigationAction.request.url {
                
                if (UIApplication.shared.canOpenURL(url)) {
                    UIApplication.shared.open(url)
                } else {
                    self.present(dialogMessage, animated: true, completion: nil)
                }
            }
            decisionHandler(.cancel)
            return
        }
        decisionHandler(.allow)
    }
     
    override func viewDidLoad() {
        super.viewDidLoad()
        let url = URL(string: "https://qr.nspk.ru/AS100001ORTF4GAF80KPJ53K186D9A3G?type=01&bank=100000000007&crc=0C8A")!
        webView.load(URLRequest(url: url))
    }
}

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val paymentURL = "https://qr.nspk.ru/AS100001ORTF4GAF80KPJ53K186D9A3G?type=01&bank=100000000007&crc=0C8A"
        val webView = findViewById<View>(R.id.webview) as WebView
        webView.webViewClient = CustomWebClient()
        webView.settings.javaScriptEnabled = true
        webView.loadUrl(paymentURL)
    }
}

class CustomWebClient : WebViewClient() {
    override fun shouldOverrideUrlLoading(view: WebView, request: WebResourceRequest): Boolean {
        val context = view.context
        try {
            context.startActivity(Intent(Intent.ACTION_VIEW, request.url))
        } catch (e: Exception) {
            Toast.makeText(
                context,
                "Приложение не поддерживает переход",
                Toast.LENGTH_SHORT
            ).show()
        }
        return true
    }
}

// Внимание! Требуется компонент react-native-webview

<WebView 
  style={{flex: 1}}
  source={{uri: state.universalLink}}
  originWhitelist={["https://*", "bank*://*"]}
  onShouldStartLoadWithRequest={async (request) => {
    if (request.url.startsWith("bank") || 
        (!request.url.includes("nspk.ru") && 
        !request.url.includes("mc.yandex.ru"))
      ) {
      try {
        await Linking.openURL(request.url)
      } catch (e) {
        alert("Не возможности найти приложение для оплаты")
      }
    }
    return true
  }}
/>

// Внимание! Требуются пакеты: webview_flutter и url_launcher

var controller = WebViewController()
  ..setJavaScriptMode(JavaScriptMode.unrestricted)
  ..setBackgroundColor(const Color(0x00000000))
  ..setNavigationDelegate(
    NavigationDelegate(
      onProgress: (int progress) {},
      onPageStarted: (String url) {},
      onPageFinished: (String url) {},
      onWebResourceError: (WebResourceError error) {},
      onNavigationRequest: (NavigationRequest request) {
        final uri = Uri.parse(request.url);
         
        if (uri.scheme.startsWith("bank") || 
            (!uri.host.contains("nspk.ru") &&
            !uri.host.contains("mc.yandex.ru"))
          ) {
          var isLaunched = false;
          try {
            isLaunched = launchUrl(uri);   
          } catch (e) {
            //
          }
           
          if (!isLaunched) {
            /* Обработка отсутствия приложения */
          }   
          return NavigationDecision.prevent;
        }
        return NavigationDecision.navigate;
      },
    ),
  )
  ..loadRequest(Uri.parse(
    'https://qr.nspk.ru/AS100001ORTF4GAF80KPJ53K186D9A3G?type=01&bank=100000000007&crc=0C8A'
  ));