moved json serialization for JavaScriptBridgeInterface to dart side, fix #64, fix #46

android/build.gradle

@@ -53,5 +53,4 @@ dependencies {
     implementation 'androidx.browser:browser:1.0.0'
     implementation 'androidx.appcompat:appcompat:1.0.2'
     implementation 'com.squareup.okhttp3:mockwebserver:3.11.0'
-    implementation 'com.google.code.gson:gson:2.8.5'
 }

android/src/main/java/com/pichillilorenzo/flutter_inappbrowser/FlutterWebView.java

@@ -4,6 +4,7 @@ import android.app.Activity;
 import android.content.Context;
 import android.util.Log;
 import android.view.View;
+import android.view.inputmethod.InputMethodManager;
 import android.webkit.WebChromeClient;
 import android.webkit.WebView;
 import android.webkit.WebViewClient;
@@ -129,6 +130,7 @@ public class FlutterWebView implements PlatformView, MethodCallHandler  {
         if (webView != null) {
           source = call.argument("source").toString();
           webView.injectScriptCode(source, result);
+          // ((InputMethodManager) this.activity.getSystemService(Context.INPUT_METHOD_SERVICE)).toggleSoftInput(0, InputMethodManager.HIDE_IMPLICIT_ONLY);
         }
         else {
           result.success("");

android/src/main/java/com/pichillilorenzo/flutter_inappbrowser/JavaScriptBridgeInterface.java

@@ -4,7 +4,6 @@ import android.os.Build;
 import android.util.Log;
 import android.webkit.JavascriptInterface;
 
-import com.google.gson.Gson;
 import com.pichillilorenzo.flutter_inappbrowser.InAppWebView.InAppWebView;
 
 import java.util.HashMap;
@@ -43,13 +42,12 @@ public class JavaScriptBridgeInterface {
 
     getChannel().invokeMethod("onCallJsHandler", obj, new MethodChannel.Result() {
       @Override
-      public void success(Object o) {
-        String json = new Gson().toJson(o);
+      public void success(Object json) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-          flutterWebView.webView.evaluateJavascript("window." + name + "[" + _callHandlerID + "](" + json + ");", null);
+          flutterWebView.webView.evaluateJavascript("window." + name + "[" + _callHandlerID + "](" + json + "); delete window." + name + "[" + _callHandlerID + "];", null);
         }
         else {
-          flutterWebView.webView.loadUrl("javascript:window." + name + "[" + _callHandlerID + "](" + json + ");");
+          flutterWebView.webView.loadUrl("javascript:window." + name + "[" + _callHandlerID + "](" + json + "); delete window." + name + "[" + _callHandlerID + "];");
         }
       }
 

example/assets/index.html

@@ -32,6 +32,7 @@
 
             window.flutter_inappbrowser.callHandler('handlerTest', 1).then(function(result) {
                 console.log(result, typeof result);
+                console.log(JSON.stringify(result));
             });
         });
 

example/lib/inline_example.screen.dart

@@ -6,6 +6,20 @@ class InlineExampleScreen extends StatefulWidget {
   _InlineExampleScreenState createState() => new _InlineExampleScreenState();
 }
 
+class User {
+  String username;
+  String password;
+
+  User({this.username, this.password});
+
+  Map<String, dynamic> toJson() {
+    return {
+      'username': this.username,
+      'password': this.password
+    };
+  }
+}
+
 class _InlineExampleScreenState extends State<InlineExampleScreen> {
   InAppWebViewController webView;
   String url = "";
@@ -40,15 +54,18 @@ class _InlineExampleScreenState extends State<InlineExampleScreen> {
           decoration:
               BoxDecoration(border: Border.all(color: Colors.blueAccent)),
           child: InAppWebView(
-            initialUrl: "https://flutter.dev/",
-            //initialFile: "assets/index.html",
+            //initialUrl: "https://mottie.github.io/Keyboard/",
+            initialFile: "assets/index.html",
             initialHeaders: {},
             initialOptions: {
-              "useShouldOverrideUrlLoading": true,
-              "useOnLoadResource": true
+              //"useShouldOverrideUrlLoading": true,
+              //"useOnLoadResource": true
             },
             onWebViewCreated: (InAppWebViewController controller) {
               webView = controller;
+              controller.addJavaScriptHandler('handlerTest', (args) {
+                return new User(username: 'user', password: 'secret');
+              });
             },
             onLoadStart: (InAppWebViewController controller, String url) {
               print("started $url");

ios/Classes/InAppWebView.swift

@@ -722,12 +722,9 @@ public class InAppWebView: WKWebView, UIScrollViewDelegate, WKUIDelegate, WKNavi
             else {
                 var json = "null"
                 if let r = result {
-                    json = JSONSerializer.toJson(r)
-                    if json == "{}" {
-                        json = "\(r)"
+                    json = r as! String
                 }
-                }
-                self.evaluateJavaScript("window.\(JAVASCRIPT_BRIDGE_NAME)[\(_callHandlerID)](\(json));", completionHandler: nil)
+                self.evaluateJavaScript("window.\(JAVASCRIPT_BRIDGE_NAME)[\(_callHandlerID)](\(json)); delete window.\(JAVASCRIPT_BRIDGE_NAME)[\(_callHandlerID)];", completionHandler: nil)
             }
         })
     }

lib/flutter_inappbrowser.dart

@@ -34,6 +34,17 @@ import 'package:uuid/uuid.dart';
 import 'package:mime/mime.dart';
 
 typedef Future<dynamic> ListenerCallback(MethodCall call);
+
+///This type represents a callback, added with [addJavaScriptHandler], that listens to post messages sent from JavaScript.
+///
+///The Android implementation uses [addJavascriptInterface](https://developer.android.com/reference/android/webkit/WebView#addJavascriptInterface(java.lang.Object,%20java.lang.String)).
+///The iOS implementation uses [addScriptMessageHandler](https://developer.apple.com/documentation/webkit/wkusercontentcontroller/1537172-addscriptmessagehandler?language=objc)
+///
+///The JavaScript function that can be used to call the handler is `window.flutter_inappbrowser.callHandler(handlerName <String>, ...args);`, where `args` are [rest parameters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters).
+///The `args` will be stringified automatically using `JSON.stringify(args)` method and then they will be decoded on the Dart side.
+///
+///Also, a [JavaScriptHandlerCallback] can return json data to the JavaScript side.
+///In this case, simply return data that you want to send and it will be automatically json encoded using [jsonEncode] from the `dart:convert` library.
 typedef dynamic JavaScriptHandlerCallback(List<dynamic> arguments);
 
 var _uuidGenerator = new Uuid();
@@ -849,7 +860,13 @@ class InAppWebViewController {
         String handlerName = call.arguments["handlerName"];
         List<dynamic> args = jsonDecode(call.arguments["args"]);
         if (javaScriptHandlersMap.containsKey(handlerName)) {
-          return await javaScriptHandlersMap[handlerName](args);
+          // convert result to json
+          try {
+            return jsonEncode(await javaScriptHandlersMap[handlerName](args));
+          } catch (error) {
+            print(error);
+            return null;
+          }
         }
         break;
       default:
@@ -1145,6 +1162,9 @@ class InAppWebViewController {
   ///
   ///The JavaScript function that can be used to call the handler is `window.flutter_inappbrowser.callHandler(handlerName <String>, ...args);`, where `args` are [rest parameters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters).
   ///The `args` will be stringified automatically using `JSON.stringify(args)` method and then they will be decoded on the Dart side.
+  ///
+  ///Also, a [JavaScriptHandlerCallback] can return json data to the JavaScript side.
+  ///In this case, simply return data that you want to send and it will be automatically json encoded using [jsonEncode] from the `dart:convert` library.
   void addJavaScriptHandler(String handlerName, JavaScriptHandlerCallback callback) {
     this.javaScriptHandlersMap[handlerName] = (callback);
   }