[webview_flutter] Fix the issue that webview cannot load assets html and local html

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java

@@ -122,6 +122,12 @@ public void onMethodCall(MethodCall methodCall, Result result) {
       case "loadUrl":
         loadUrl(methodCall, result);
         break;
+      case "loadAssetHtmlFile":
+        loadAssetHtmlFile(methodCall, result);
+        break;
+      case "loadLocalHtmlFile":
+        loadLocalHtmlFile(methodCall, result);
+        break;
       case "updateSettings":
         updateSettings(methodCall, result);
         break;
@@ -175,6 +181,18 @@ private void loadUrl(MethodCall methodCall, Result result) {
     result.success(null);
   }
 
+  private void loadAssetHtmlFile(MethodCall methodCall, Result result) {
+    String url = (String) methodCall.arguments;
+    webView.loadUrl("file:///android_asset/flutter_assets/" + url);
+    result.success(null);
+  }
+
+  private void loadLocalHtmlFile(MethodCall methodCall, Result result) {
+    String url = (String) methodCall.arguments;
+    webView.loadUrl("file:///" + url);
+    result.success(null);
+  }
+
   private void canGoBack(Result result) {
     result.success(webView.canGoBack());
   }

packages/webview_flutter/ios/Classes/FLTWebViewFlutterPlugin.m

@@ -9,8 +9,7 @@
 @implementation FLTWebViewFlutterPlugin
 
 + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
-  FLTWebViewFactory* webviewFactory =
-      [[FLTWebViewFactory alloc] initWithMessenger:registrar.messenger];
+  FLTWebViewFactory* webviewFactory = [[FLTWebViewFactory alloc] initWithRegistrar:registrar];
   [registrar registerViewFactory:webviewFactory withId:@"plugins.flutter.io/webview"];
   [FLTCookieManager registerWithRegistrar:registrar];
 }

packages/webview_flutter/ios/Classes/FlutterWebView.h

@@ -12,13 +12,13 @@ NS_ASSUME_NONNULL_BEGIN
 - (instancetype)initWithFrame:(CGRect)frame
                viewIdentifier:(int64_t)viewId
                     arguments:(id _Nullable)args
-              binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;
+                    registrar:(NSObject<FlutterPluginRegistrar>*)registrar;
 
 - (UIView*)view;
 @end
 
 @interface FLTWebViewFactory : NSObject <FlutterPlatformViewFactory>
-- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;
+- (instancetype)initWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar;
 @end
 
 /**

packages/webview_flutter/ios/Classes/FlutterWebView.m

@@ -8,12 +8,14 @@
 
 @implementation FLTWebViewFactory {
   NSObject<FlutterBinaryMessenger>* _messenger;
+  NSObject<FlutterPluginRegistrar>* _registrar;
 }
 
-- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
+- (instancetype)initWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
   self = [super init];
   if (self) {
-    _messenger = messenger;
+    _registrar = registrar;
+    _messenger = registrar.messenger;
   }
   return self;
 }
@@ -28,7 +30,7 @@ - (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
   FLTWebViewController* webviewController = [[FLTWebViewController alloc] initWithFrame:frame
                                                                          viewIdentifier:viewId
                                                                               arguments:args
-                                                                        binaryMessenger:_messenger];
+                                                                              registrar:_registrar];
   return webviewController;
 }
 
@@ -64,17 +66,19 @@ @implementation FLTWebViewController {
   // The set of registered JavaScript channel names.
   NSMutableSet* _javaScriptChannelNames;
   FLTWKNavigationDelegate* _navigationDelegate;
+  NSObject<FlutterPluginRegistrar>* _registrar;
 }
 
 - (instancetype)initWithFrame:(CGRect)frame
                viewIdentifier:(int64_t)viewId
                     arguments:(id _Nullable)args
-              binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
+                    registrar:(nonnull NSObject<FlutterPluginRegistrar>*)registrar {
   if (self = [super init]) {
     _viewId = viewId;
-
+    _registrar = registrar;
     NSString* channelName = [NSString stringWithFormat:@"plugins.flutter.io/webview_%lld", viewId];
-    _channel = [FlutterMethodChannel methodChannelWithName:channelName binaryMessenger:messenger];
+    _channel = [FlutterMethodChannel methodChannelWithName:channelName
+                                           binaryMessenger:_registrar.messenger];
     _javaScriptChannelNames = [[NSMutableSet alloc] init];
 
     WKUserContentController* userContentController = [[WKUserContentController alloc] init];
@@ -128,6 +132,10 @@ - (void)onMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
     [self onUpdateSettings:call result:result];
   } else if ([[call method] isEqualToString:@"loadUrl"]) {
     [self onLoadUrl:call result:result];
+  } else if ([[call method] isEqualToString:@"loadAssetHtmlFile"]) {
+    [self onLoadAssetHtmlFile:call result:result];
+  } else if ([[call method] isEqualToString:@"loadLocalHtmlFile"]) {
+    [self onLoadLocalHtmlFile:call result:result];
   } else if ([[call method] isEqualToString:@"canGoBack"]) {
     [self onCanGoBack:call result:result];
   } else if ([[call method] isEqualToString:@"canGoForward"]) {
@@ -175,6 +183,28 @@ - (void)onLoadUrl:(FlutterMethodCall*)call result:(FlutterResult)result {
   }
 }
 
+- (void)onLoadAssetHtmlFile:(FlutterMethodCall*)call result:(FlutterResult)result {
+  NSString* url = [call arguments];
+  if (![self loadAssetHtmlFile:url]) {
+    result([FlutterError errorWithCode:@"loadAssetHtmlFile_failed"
+                               message:@"Failed parsing the URL"
+                               details:[NSString stringWithFormat:@"URL was: '%@'", url]]);
+  } else {
+    result(nil);
+  }
+}
+
+- (void)onLoadLocalHtmlFile:(FlutterMethodCall*)call result:(FlutterResult)result {
+  NSString* url = [call arguments];
+  if (![self loadLocalHtmlFile:url]) {
+    result([FlutterError errorWithCode:@"loadAssetHtmlFile_failed"
+                               message:@"Failed parsing the URL"
+                               details:[NSString stringWithFormat:@"URL was: '%@'", url]]);
+  } else {
+    result(nil);
+  }
+}
+
 - (void)onCanGoBack:(FlutterMethodCall*)call result:(FlutterResult)result {
   BOOL canGoBack = [_webView canGoBack];
   result([NSNumber numberWithBool:canGoBack]);
@@ -374,6 +404,58 @@ - (bool)loadUrl:(NSString*)url withHeaders:(NSDictionary<NSString*, NSString*>*)
   return true;
 }
 
+- (bool)loadAssetHtmlFile:(NSString*)url {
+  NSArray* array = [url componentsSeparatedByString:@"?"];
+  NSString* pathString = [array objectAtIndex:0];
+  NSLog(@"%@%@", @"pathString: ", pathString);
+  NSString* key = [_registrar lookupKeyForAsset:pathString];
+  NSURL* baseURL = [[NSBundle mainBundle] URLForResource:key withExtension:nil];
+  if (!baseURL) {
+    return false;
+  }
+  NSURL* newUrl = baseURL;
+  if ([array count] > 1) {
+    NSString* queryString = [array objectAtIndex:1];
+    NSLog(@"%@%@", @"queryString: ", queryString);
+    NSString* queryPart = [NSString stringWithFormat:@"%@%@", @"?", queryString];
+    NSLog(@"%@%@", @"queryPart: ", queryPart);
+    newUrl = [NSURL URLWithString:queryPart relativeToURL:baseURL];
+  }
+  if (@available(iOS 9.0, *)) {
+    [_webView loadFileURL:newUrl allowingReadAccessToURL:[NSURL URLWithString:@"file:///"]];
+  } else {
+    return false;
+  }
+  return true;
+}
+
+- (bool)loadLocalHtmlFile:(NSString*)url {
+  NSArray* array = [url componentsSeparatedByString:@"?"];
+  NSString* pathString = [array objectAtIndex:0];
+  NSLog(@"%@%@", @"pathString: ", pathString);
+  NSString* key = [_registrar lookupKeyForAsset:pathString];
+  NSURL* baseURL = [[NSBundle mainBundle] URLForResource:key withExtension:nil];
+  if (!baseURL) {
+    [_webView loadFileURL:[NSURL fileURLWithPath:pathString]
+        allowingReadAccessToURL:[NSURL fileURLWithPath:pathString]];
+    return true;
+  }
+  NSURL* newUrl = baseURL;
+  if ([array count] > 1) {
+    NSString* queryString = [array objectAtIndex:1];
+    NSLog(@"%@%@", @"queryString: ", queryString);
+    NSString* queryPart = [NSString stringWithFormat:@"%@%@", @"?", queryString];
+    NSLog(@"%@%@", @"queryPart: ", queryPart);
+    newUrl = [NSURL URLWithString:queryPart relativeToURL:baseURL];
+  }
+  if (@available(iOS 9.0, *)) {
+    [_webView loadFileURL:newUrl allowingReadAccessToURL:[NSURL URLWithString:@"file:///"]];
+  } else {
+    return false;
+  }
+  return true;
+}
+
 - (void)registerJavaScriptChannels:(NSSet*)channelNames
                         controller:(WKUserContentController*)userContentController {
   for (NSString* channelName in channelNames) {

packages/webview_flutter/lib/platform_interface.dart

@@ -64,6 +64,26 @@ abstract class WebViewPlatformController {
         "WebView loadUrl is not implemented on the current platform");
   }
 
+  /// Load html file from local path
+  ///
+  /// `url` must not be null.
+  ///
+  /// Throws an ArgumentError if `url` is not a valid URL string.
+  Future<void> loadAssetHtmlFile(String url) {
+    throw UnimplementedError(
+        "WebView loadAssetHtmlFile is not implemented on the current platform");
+  }
+
+  /// Load html file from local path
+  ///
+  /// `url` must not be null.
+  ///
+  /// Throws an ArgumentError if `url` is not a valid URL string.
+  Future<void> loadLocalHtmlFile(String url) {
+    throw UnimplementedError(
+        "WebView loadLocalHtmlFile is not implemented on the current platform");
+  }
+
   /// Updates the webview settings.
   ///
   /// Any non null field in `settings` will be set as the new setting value.

packages/webview_flutter/lib/src/webview_method_channel.dart

@@ -60,6 +60,14 @@ class MethodChannelWebViewPlatform implements WebViewPlatformController {
     });
   }
 
+  @override
+  Future<void> loadAssetHtmlFile(String url) =>
+      _channel.invokeMethod<String>('loadAssetHtmlFile', url);
+
+  @override
+  Future<void> loadLocalHtmlFile(String url) =>
+      _channel.invokeMethod<String>('loadLocalHtmlFile', url);
+
   @override
   Future<String> currentUrl() => _channel.invokeMethod<String>('currentUrl');
 

packages/webview_flutter/lib/webview_flutter.dart

@@ -531,6 +531,22 @@ class WebViewController {
     return _webViewPlatformController.loadUrl(url, headers);
   }
 
+  /// Load html file from assets
+  ///
+  /// `url` must not be null.
+  Future<void> loadAssetHtmlFile(String url) async {
+    assert(url != null);
+    return _webViewPlatformController.loadAssetHtmlFile(url);
+  }
+
+  /// Load html file from local path
+  ///
+  /// `url` must not be null.
+  Future<void> loadLocalHtmlFile(String url) async {
+    assert(url != null);
+    return _webViewPlatformController.loadLocalHtmlFile(url);
+  }
+
   /// Accessor to the current URL that the WebView is displaying.
   ///
   /// If [WebView.initialUrl] was never specified, returns `null`.