Upload File in Nativescript Webview with iframe

My problem is I have one webview Containing Dynamic Form or form which is created dynamic with WP Builders and that is included in iframe and i want to select file from application in nativescript this will not allow me select file.

So I want to try

How to load files into webview in native script

http://shripalsoni.com/blog/nativescript-webview-native-bi-directional-communication/

But problem is form is dynamic is there any script which will detect click event of file input inside frame and also put file path to it when file is selected if we can detect event for file input click.

another issue is what if there are more than one file input in dynamic form

I Got Answer by Implementing WebChromeClient In android

 let webview: WebView = this.webViewRef.nativeElement;
 let myWebChromeClient: MyWebChromeClient = new MyWebChromeClient();
 webview.android.setWebChromeClient(myWebChromeClient);

and class MyWebChromeClient is here

import * as imagepicker from "nativescript-imagepicker";
import * as fs from "file-system";

export class MyWebChromeClient extends android.webkit.WebChromeClient {
    file_path:string;
    constructor() {
        super();

        return global.__native(this);
    }

    onShowFileChooser(webView,filePathCallback,fileChooserParams) {

         this.filepathCallback(filePathCallback);

        return true;
    }

    filepathCallback(filePathCallback)
    {
        let context = imagepicker.create({
            mode: "single",
            mediaType: imagepicker.ImagePickerMediaType.Any
        });
       this.startSelection(context,filePathCallback);
    }

    startSelection(context,filePathCallback) {
        context.authorize().then(() => {
                                    return context.present();
                                  })
            .then((selection) => {
                selection.forEach((selected) => {
                    let path = selected.android;
                    let file = fs.File.fromPath(path);
                    this.file_path = file.path;
                    this.file_path = "file://" + this.file_path;
                    let results = Array.create(android.net.Uri, 1);
                    results[0] = android.net.Uri.parse(this.file_path);

                    filePathCallback.onReceiveValue(results);
                    return this.file_path;
                });
            }).catch(function (e) {
                console.log(e);
            });
    }
}