added return value for JavaScriptHandlerCallback, added...

added return value for JavaScriptHandlerCallback, added flutterInAppBrowserPlatformReady event for javascript, breaking change: javaScriptHandlersMap contains only one callback

android/build.gradle

@@ -53,4 +53,5 @@ 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/InAppWebView/InAppWebView.java

@@ -76,6 +76,8 @@ public class InAppWebView extends WebView {
           "   }" +
           "})();";
 
+  static final String platformReadyJS = "window.dispatchEvent(new Event('flutterInAppBrowserPlatformReady'));";
+
   public InAppWebView(Context context) {
     super(context);
   }

android/src/main/java/com/pichillilorenzo/flutter_inappbrowser/InAppWebView/InAppWebViewClient.java

@@ -11,6 +11,7 @@ import android.webkit.CookieManager;
 import android.webkit.CookieSyncManager;
 import android.webkit.HttpAuthHandler;
 import android.webkit.SslErrorHandler;
+import android.webkit.ValueCallback;
 import android.webkit.WebResourceRequest;
 import android.webkit.WebResourceResponse;
 import android.webkit.WebView;
@@ -195,7 +196,7 @@ public class InAppWebViewClient extends WebViewClient {
   }
 
 
-  public void onPageFinished(WebView view, String url) {
+  public void onPageFinished(final WebView view, String url) {
     super.onPageFinished(view, url);
 
     ((inAppBrowserActivity != null) ? inAppBrowserActivity.webView : flutterWebView.webView).isLoading = false;
@@ -213,11 +214,18 @@ public class InAppWebViewClient extends WebViewClient {
 
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
       view.evaluateJavascript(InAppWebView.consoleLogJS, null);
-      view.evaluateJavascript(JavaScriptBridgeInterface.flutterInAppBroserJSClass, null);
+      view.evaluateJavascript(JavaScriptBridgeInterface.flutterInAppBroserJSClass, new ValueCallback<String>() {
+        @Override
+        public void onReceiveValue(String value) {
+          view.evaluateJavascript(InAppWebView.platformReadyJS, null);
+        }
+      });
+
     }
     else {
       view.loadUrl("javascript:"+InAppWebView.consoleLogJS);
       view.loadUrl("javascript:"+JavaScriptBridgeInterface.flutterInAppBroserJSClass);
+      view.loadUrl("javascript:"+InAppWebView.platformReadyJS);
     }
 
     Map<String, Object> obj = new HashMap<>();

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

 package com.pichillilorenzo.flutter_inappbrowser;
 
+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;
 import java.util.Map;
 
@@ -14,7 +19,11 @@ public class JavaScriptBridgeInterface {
   private InAppBrowserActivity inAppBrowserActivity;
 
   public static final String flutterInAppBroserJSClass = "window." + name + ".callHandler = function(handlerName, ...args) {" +
-    "window." + name + "._callHandler(handlerName, JSON.stringify(args));" +
+    "var _callHandlerID = setTimeout(function(){});" +
+    "window." + name + "._callHandler(handlerName, _callHandlerID, JSON.stringify(args));" +
+    "return new Promise(function(resolve, reject) {" +
+    "  window." + name + "[_callHandlerID] = resolve;" +
+    "});" +
   "}";
 
   public JavaScriptBridgeInterface(Object obj) {
@@ -25,13 +34,35 @@ public class JavaScriptBridgeInterface {
   }
 
   @JavascriptInterface
-  public void _callHandler(String handlerName, String args) {
+  public void _callHandler(String handlerName, final String _callHandlerID, String args) {
     Map<String, Object> obj = new HashMap<>();
     if (inAppBrowserActivity != null)
       obj.put("uuid", inAppBrowserActivity.uuid);
     obj.put("handlerName", handlerName);
     obj.put("args", args);
-    getChannel().invokeMethod("onCallJsHandler", obj);
+
+    getChannel().invokeMethod("onCallJsHandler", obj, new MethodChannel.Result() {
+      @Override
+      public void success(Object o) {
+        String json = new Gson().toJson(o);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+          flutterWebView.webView.evaluateJavascript("window." + name + "[" + _callHandlerID + "](" + json + ");", null);
+        }
+        else {
+          flutterWebView.webView.loadUrl("javascript:window." + name + "[" + _callHandlerID + "](" + json + ");");
+        }
+      }
+
+      @Override
+      public void error(String s, String s1, Object o) {
+        Log.d(LOG_TAG, "ERROR: " + s + " " + s1);
+      }
+
+      @Override
+      public void notImplemented() {
+
+      }
+    });
   }
 
   private MethodChannel getChannel() {

example/assets/index.html

@@ -27,7 +27,14 @@
         </div>
     </div>
     <script>
-        console.log("hello");
+        window.addEventListener("flutterInAppBrowserPlatformReady", function(event) {
+            console.log("ready");
+
+            window.flutter_inappbrowser.callHandler('handlerTest', 1).then(function(result) {
+                console.log(result, typeof result);
+            });
+        });
+
     </script>
 </div>
 </body>

example/lib/inline_example.screen.dart

@@ -41,6 +41,7 @@ class _InlineExampleScreenState extends State<InlineExampleScreen> {
               BoxDecoration(border: Border.all(color: Colors.blueAccent)),
           child: InAppWebView(
             initialUrl: "https://flutter.dev/",
+            //initialFile: "assets/index.html",
             initialHeaders: {},
             initialOptions: {
               "useShouldOverrideUrlLoading": true,
@@ -55,7 +56,7 @@ class _InlineExampleScreenState extends State<InlineExampleScreen> {
                 this.url = url;
               });
             },
-            onLoadStop: (InAppWebViewController controller, String url) {
+            onLoadStop: (InAppWebViewController controller, String url) async {
               print("stopped $url");
             },
             onProgressChanged:
@@ -70,7 +71,10 @@ class _InlineExampleScreenState extends State<InlineExampleScreen> {
             },
             onLoadResource: (InAppWebViewController controller, WebResourceResponse response, WebResourceRequest request) {
               print("resource " + request.url);
-            }
+            },
+            onConsoleMessage: (InAppWebViewController controller, ConsoleMessage consoleMessage) {
+              print(consoleMessage.message);
+            },
           ),
         ),
       ),

flutter_inappbrowser.iml

@@ -20,8 +20,6 @@
       <excludeFolder url="file://$MODULE_DIR$/example/ios/.symlinks/plugins/flutter_inappbrowser/example/.dart_tool" />
       <excludeFolder url="file://$MODULE_DIR$/example/ios/.symlinks/plugins/flutter_inappbrowser/example/.pub" />
       <excludeFolder url="file://$MODULE_DIR$/example/ios/.symlinks/plugins/flutter_inappbrowser/example/build" />
-      <excludeFolder url="file://$MODULE_DIR$/example/ios/.symlinks/plugins/flutter_inappbrowser/example/ios/Flutter/App.framework/flutter_assets/packages" />
-      <excludeFolder url="file://$MODULE_DIR$/example/ios/.symlinks/plugins/flutter_inappbrowser/example/ios/Flutter/flutter_assets/packages" />
       <excludeFolder url="file://$MODULE_DIR$/example/ios/Flutter/App.framework/flutter_assets/packages" />
       <excludeFolder url="file://$MODULE_DIR$/example/ios/Flutter/flutter_assets/packages" />
     </content>

ios/Classes/InAppWebView.swift

@@ -5,6 +5,7 @@
 //  Created by Lorenzo on 21/10/18.
 //
 
+import Flutter
 import Foundation
 import WebKit
 
@@ -71,10 +72,16 @@ let JAVASCRIPT_BRIDGE_NAME = "flutter_inappbrowser"
 let javaScriptBridgeJS = """
 window.\(JAVASCRIPT_BRIDGE_NAME) = {};
 window.\(JAVASCRIPT_BRIDGE_NAME).callHandler = function(handlerName, ...args) {
-    window.webkit.messageHandlers['callHandler'].postMessage( {'handlerName': handlerName, 'args': JSON.stringify(args)} );
+    var _callHandlerID = setTimeout(function(){});
+    window.webkit.messageHandlers['callHandler'].postMessage( {'handlerName': handlerName, '_callHandlerID': _callHandlerID, 'args': JSON.stringify(args)} );
+    return new Promise(function(resolve, reject) {
+        window.\(JAVASCRIPT_BRIDGE_NAME)[_callHandlerID] = resolve;
+    });
 }
 """
 
+let platformReadyJS = "window.dispatchEvent(new Event('flutterInAppBrowserPlatformReady'));";
+
 public class InAppWebView: WKWebView, UIScrollViewDelegate, WKUIDelegate, WKNavigationDelegate, WKScriptMessageHandler {
     
     var IABController: InAppBrowserWebViewController?
@@ -235,12 +242,14 @@ public class InAppWebView: WKWebView, UIScrollViewDelegate, WKUIDelegate, WKNavi
     public func loadUrl(url: URL, headers: [String: String]?) {
         var request = URLRequest(url: url)
         currentURL = url
+        if headers != nil {
             if let mutableRequest = (request as NSURLRequest).mutableCopy() as? NSMutableURLRequest {
                 for (key, value) in headers! {
                     mutableRequest.setValue(value, forHTTPHeaderField: key)
                 }
                 request = mutableRequest as URLRequest
             }
+        }
         load(request)
     }
     
@@ -581,6 +590,7 @@ public class InAppWebView: WKWebView, UIScrollViewDelegate, WKUIDelegate, WKNavi
         self.WKNavigationMap = [:]
         currentURL = url
         onLoadStop(url: (currentURL?.absoluteString)!)
+        evaluateJavaScript(platformReadyJS, completionHandler: nil)
         
         if IABController != nil {
             IABController!.updateUrlTextField(url: (currentURL?.absoluteString)!)
@@ -698,12 +708,28 @@ public class InAppWebView: WKWebView, UIScrollViewDelegate, WKUIDelegate, WKNavi
         getChannel().invokeMethod("onConsoleMessage", arguments: arguments)
     }
     
-    public func onCallJsHandler(handlerName: String, args: String) {
+    public func onCallJsHandler(handlerName: String, _callHandlerID: Int64, args: String) {
         var arguments: [String: Any] = ["handlerName": handlerName, "args": args]
         if IABController != nil {
             arguments["uuid"] = IABController!.uuid
         }
-        getChannel().invokeMethod("onCallJsHandler", arguments: arguments)
+        
+        getChannel().invokeMethod("onCallJsHandler", arguments: arguments, result: {(result) -> Void in
+            if result is FlutterError {
+                print((result as! FlutterError).message)
+            }
+            else if (result as? NSObject) == FlutterMethodNotImplemented {}
+            else {
+                var json = "null"
+                if let r = result {
+                    json = JSONSerializer.toJson(r)
+                    if json == "{}" {
+                        json = "\(r)"
+                    }
+                }
+                self.evaluateJavaScript("window.\(JAVASCRIPT_BRIDGE_NAME)[\(_callHandlerID)](\(json));", completionHandler: nil)
+            }
+        })
     }
     
     public func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
@@ -765,8 +791,9 @@ public class InAppWebView: WKWebView, UIScrollViewDelegate, WKUIDelegate, WKNavi
         else if message.name == "callHandler" {
             let body = message.body as! [String: Any]
             let handlerName = body["handlerName"] as! String
+            let _callHandlerID = body["_callHandlerID"] as! Int64
             let args = body["args"] as! String
-            onCallJsHandler(handlerName: handlerName, args: args)
+            onCallJsHandler(handlerName: handlerName, _callHandlerID: _callHandlerID, args: args)
         }
     }
     

lib/flutter_inappbrowser.dart

@@ -34,7 +34,7 @@ import 'package:uuid/uuid.dart';
 import 'package:mime/mime.dart';
 
 typedef Future<dynamic> ListenerCallback(MethodCall call);
-typedef Future<void> JavaScriptHandlerCallback(List<dynamic> arguments);
+typedef dynamic JavaScriptHandlerCallback(List<dynamic> arguments);
 
 var _uuidGenerator = new Uuid();
 
@@ -112,7 +112,7 @@ class _ChannelManager {
 class InAppBrowser {
 
   String uuid;
-  Map<String, List<JavaScriptHandlerCallback>> javaScriptHandlersMap = HashMap<String, List<JavaScriptHandlerCallback>>();
+  Map<String, JavaScriptHandlerCallback> javaScriptHandlersMap = HashMap<String, JavaScriptHandlerCallback>();
   bool _isOpened = false;
   /// WebView Controller that can be used to access the [InAppWebView] API.
   InAppWebViewController webViewController;
@@ -735,7 +735,7 @@ class InAppWebViewController {
 
   InAppWebView _widget;
   MethodChannel _channel;
-  Map<String, List<JavaScriptHandlerCallback>> javaScriptHandlersMap = HashMap<String, List<JavaScriptHandlerCallback>>();
+  Map<String, JavaScriptHandlerCallback> javaScriptHandlersMap = HashMap<String, JavaScriptHandlerCallback>();
   bool _isOpened = false;
   int _id;
   String _inAppBrowserUuid;
@@ -849,9 +849,7 @@ class InAppWebViewController {
         String handlerName = call.arguments["handlerName"];
         List<dynamic> args = jsonDecode(call.arguments["args"]);
         if (javaScriptHandlersMap.containsKey(handlerName)) {
-          for (var handler in javaScriptHandlersMap[handlerName]) {
-            handler(args);
-          }
+          return await javaScriptHandlersMap[handlerName](args);
         }
         break;
       default:
@@ -1140,31 +1138,22 @@ class InAppWebViewController {
     await _channel.invokeMethod('injectStyleFile', args);
   }
 
-  ///Adds/Appends a JavaScript message handler [callback] ([JavaScriptHandlerCallback]) that listen to post messages sent from JavaScript by the handler with name [handlerName].
-  ///Returns the position `index` of the handler that can be used to remove it with the [removeJavaScriptHandler()] method.
+  ///Adds a JavaScript message handler [callback] ([JavaScriptHandlerCallback]) that listen to post messages sent from JavaScript by the handler with name [handlerName].
   ///
   ///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.
-  int addJavaScriptHandler(String handlerName, JavaScriptHandlerCallback callback) {
-    this.javaScriptHandlersMap.putIfAbsent(handlerName, () => List<JavaScriptHandlerCallback>());
-    this.javaScriptHandlersMap[handlerName].add(callback);
-    return this.javaScriptHandlersMap[handlerName].indexOf(callback);
+  void addJavaScriptHandler(String handlerName, JavaScriptHandlerCallback callback) {
+    this.javaScriptHandlersMap[handlerName] = (callback);
   }
 
-  ///Removes a JavaScript message handler previously added with the [addJavaScriptHandler()] method in the [handlerName] list by its position [index].
-  ///Returns `true` if the callback is removed, otherwise `false`.
-  bool removeJavaScriptHandler(String handlerName, int index) {
-    try {
-      this.javaScriptHandlersMap[handlerName].removeAt(index);
-      return true;
-    }
-    on RangeError catch(e) {
-      print(e);
-    }
-    return false;
+  ///Removes a JavaScript message handler previously added with the [addJavaScriptHandler()] associated to [handlerName] key.
+  ///Returns the value associated with [handlerName] before it was removed.
+  ///Returns `null` if [handlerName] was not found.
+  JavaScriptHandlerCallback removeJavaScriptHandler(String handlerName) {
+    return this.javaScriptHandlersMap.remove(handlerName);
   }
 
   ///Takes a screenshot (in PNG format) of the WebView's visible viewport and returns a `Uint8List`. Returns `null` if it wasn't be able to take it.

pubspec.yaml

 name: flutter_inappbrowser
 description: A Flutter plugin that allows you to add an inline webview or open an in-app browser window (inspired by the popular cordova-plugin-inappbrowser).
-version: 1.0.1
+version: 1.1.0
 author: Lorenzo Pichilli <pichillilorenzo@gmail.com>
 homepage: https://github.com/pichillilorenzo/flutter_inappbrowser