Hey there! Let's work through this Web NFC permission issue in your Android WebView. That NotAllowedError pops up because WebView needs a bit more setup beyond just enabling JavaScript to grant access to NFC features. Here's what you need to fix step by step:

1. Add NFC Permissions to Your Manifest #

First, you need to declare that your app uses NFC in the AndroidManifest.xml file. Add these lines right before the <application> tag:

<uses-permission android:name="android.permission.NFC" />
<uses-feature android:name="android.hardware.nfc" android:required="true" />

• The <uses-permission> line lets your app request access to NFC hardware.
• The <uses-feature> line tells Google Play to only show your app to devices that support NFC (you can set required="false" if you want your app to work on non-NFC devices too).

2. Handle Permission Requests in WebView #

WebView won't automatically prompt for or grant NFC permissions like a regular browser does. You need to set up a WebChromeClient and override its onPermissionRequest method to explicitly grant NFC access when requested by the web content.

Update your MainActivity.kt code with these changes:

• Add imports for android.webkit.WebChromeClient and android.webkit.PermissionRequest.
• Replace your existing WebView setup with code that includes the WebChromeClient override.

Here's how the updated onCreate method will look:

@SuppressLint("SetJavaScriptEnabled")
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    webView = findViewById(R.id.webView)
    urlInput = findViewById(R.id.urlInput)
    goButton = findViewById(R.id.goButton)

    webView.webViewClient = WebViewClient()
    webView.settings.javaScriptEnabled = true

    // Add this WebChromeClient to handle NFC permission requests
    webView.webChromeClient = object : WebChromeClient() {
        override fun onPermissionRequest(request: PermissionRequest?) {
            request?.let { permissionRequest ->
                // Check if the request is for NFC access
                if (permissionRequest.resources.contains(PermissionRequest.RESOURCE_NFC)) {
                    // Grant the NFC permission
                    permissionRequest.grant(permissionRequest.resources)
                } else {
                    // Deny other unneeded permissions (adjust as per your app's needs)
                    permissionRequest.deny()
                }
            }
        }
    }

    goButton.setOnClickListener {
        var url = urlInput.text.toString().trim()
        if (!url.startsWith("http://") && !url.startsWith("https://")) {
            url = "https://$url"
        }
        webView.loadUrl(url)
    }
}

3. Ensure Minimum API Level is 29 or Higher #

Web NFC support in Android WebView was introduced in Android 10 (API level 29). Open your module-level build.gradle file and set the minimum SDK version to at least 29:

android {
    defaultConfig {
        minSdkVersion 29
        targetSdkVersion 34 // Use the latest stable SDK version
    }
}

4. Optional: Add Device NFC Checks (For Better User Experience) #

To avoid confusion, you can add code to check if the device supports NFC and if it's enabled before loading the web content. Add this inside your goButton click listener:

val nfcAdapter = NfcAdapter.getDefaultAdapter(this)
if (nfcAdapter == null) {
    Toast.makeText(this, "This device doesn't support NFC", Toast.LENGTH_SHORT).show()
    return@setOnClickListener
}
if (!nfcAdapter.isEnabled) {
    // Prompt user to turn on NFC in settings
    val intent = Intent(Settings.ACTION_NFC_SETTINGS)
    startActivity(intent)
    return@setOnClickListener
}

For this, you'll need to add these imports at the top of MainActivity.kt:

import android.nfc.NfcAdapter
import android.widget.Toast
import android.provider.Settings

Final Notes #

• Always test on a physical Android device (emulators don't support NFC functionality).
• Make sure the web content you're loading uses HTTPS (your code already handles this automatically, which is perfect because Web NFC only works with secure origins).

Give these changes a try, and your WebView should now grant the necessary NFC permissions to the web content! Let me know if you run into any other issues along the way.