Flutetr webview加载本地html 无法加载js文件

Flutter官方的webview_flutter ios中使用的wkwebview来实现的，webview加载本地html 无法加载js文件， 网上找了很多方法都不行、后来发现只要在FlutterWebview initWithFrame方法中加上这一句话就好了，另外注意需要在当前app的沙盒中。

  [configuration.preferences setValue:@YES forKey:@"allowFileAccessFromFileURLs"];

完整的代码

- (instancetype)initWithFrame:(CGRect)frame
               viewIdentifier:(int64_t)viewId
                    arguments:(id _Nullable)args
              binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
  if (self = [super init]) {
    _viewId = viewId;

    NSString* channelName = [NSString stringWithFormat:@"plugins.flutter.io/webview_%lld", viewId];
    _channel = [FlutterMethodChannel methodChannelWithName:channelName binaryMessenger:messenger];
    _javaScriptChannelNames = [[NSMutableSet alloc] init];

    WKUserContentController* userContentController = [[WKUserContentController alloc] init];
    if ([args[@"javascriptChannelNames"] isKindOfClass:[NSArray class]]) {
      NSArray* javaScriptChannelNames = args[@"javascriptChannelNames"];
      [_javaScriptChannelNames addObjectsFromArray:javaScriptChannelNames];
      [self registerJavaScriptChannels:_javaScriptChannelNames controller:userContentController];
    }

    NSDictionary<NSString*, id>* settings = args[@"settings"];

    WKWebViewConfiguration* configuration = [[WKWebViewConfiguration alloc] init];
      
//      WKUserScript *script = [[WKUserScript alloc] initWithSource:[self jsString] injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];
//      [configuration.userContentController addUserScript:script];
      [configuration.preferences setValue:@YES forKey:@"allowFileAccessFromFileURLs"];
      
    configuration.userContentController = userContentController;
    [self updateAutoMediaPlaybackPolicy:args[@"autoMediaPlaybackPolicy"]
                        inConfiguration:configuration];

    _webView = [[FLTWKWebView alloc] initWithFrame:frame configuration:configuration];
    _navigationDelegate = [[FLTWKNavigationDelegate alloc] initWithChannel:_channel];
    _webView.UIDelegate = self;
    _webView.navigationDelegate = _navigationDelegate;
    __weak __typeof__(self) weakSelf = self;
    [_channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
      [weakSelf onMethodCall:call result:result];
    }];

    if (@available(iOS 11.0, *)) {
      _webView.scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
      if (@available(iOS 13.0, *)) {
        _webView.scrollView.automaticallyAdjustsScrollIndicatorInsets = NO;
      }
    }

    [self applySettings:settings];
    // TODO(amirh): return an error if apply settings failed once it's possible to do so.
    // https://github.com/flutter/flutter/issues/36228

    NSString* initialUrl = args[@"initialUrl"];
    if ([initialUrl isKindOfClass:[NSString class]]) {
      [self loadUrl:initialUrl];
    }
  }
  return self;
}

android的话增加这句话，容许加载本地文件url

      webView.getSettings().setAllowFileAccessFromFileURLs(true);

以下方法是几种不行的方法尝试；也是作下记录。

//- (bool)loadUrl:(NSString*)url withHeaders:(NSDictionary<NSString*, NSString*>*)headers {
//  NSURL* nsUrl = [NSURL URLWithString:url];
//  if (!nsUrl) {
//    return false;
//  }
//  NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:nsUrl];
//  [request setAllHTTPHeaderFields:headers];
////判断是url，然后使用不同的加载方式
//  if([url hasPrefix:@"http"]) {
//      [_webView loadRequest:request];
//      NSLog(@"zb....%@",@"loadRequest");
//  }else{
//      [_webView loadFileURL:nsUrl allowingReadAccessToURL:[nsUrl URLByDeletingLastPathComponent]];
//
//      //      NSURL *pathURL = [NSURL fileURLWithPath:url];
////        NSURL* nsUrl = [NSURL URLWithString:@"file:///Users/zhoubo5/jdflutter_webview/dart_2_js_web_example/build/web"];
////
////      NSString *document = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
////
////      NSString *path = [document stringByAppendingString:@"/web/index.html"];
////      NSURL *pathURL = [NSURL fileURLWithPath:path];
////      NSString *path1 = [document stringByAppendingString:@"/web"];
////      NSURL *pathURL2 = [NSURL fileURLWithPath:path1];
//
////      NSURL *accessURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] objectAtIndex:0];
////      [self.webview loadFileURL:self.url allowingReadAccessToURL:accessURL];
//
////       [_webView loadFileURL:pathURL allowingReadAccessToURL:pathURL2];
//
//
//
////      //项目中的文件夹路径
////      NSString *directoryPath = [NSFileManager appSourceName:@"FeedbackH5" andType:@""];
////
////      //tmp缓存文件夹路径
////      NSString *tmpPath = [KFileManger tmpPath];
////
////      //新文件夹名字
////      NSString *wwwDir =@"www";
////
////      //tmp文件夹下创建www文件夹
////      [KFileManger createDirWithPath:tmpPath andDirectoryName: wwwDir];
////
////      //tmp中的www文件夹中的路径
////      NSString *tmpWWW = [tmpPath stringByAppendingString: wwwDir];
////
////      //copy文件夹到 tmp/www 路径下
////      [KFileManger copyMissingFile:directoryPath toPath:tmpWWW];
////
////      // 字符 tmp/www/FeedbackH5/pages/feedback.html 全路径
////      NSString *tmpWWWFeedback = [tmpWWW stringByAppendingString:@"/FeedbackH5/pages/feedback.html"];
////
////      //tmp 操作，字符转换成URL
////      NSURL *feedbackURL = [NSURL fileURLWithPath:tmpWWWFeedback];
////
////      //WKWebView加载
////      [_webView loadRequest:[NSURLRequest requestWithURL:feedbackURL]];
//
////         WKWebView *webView  =[[WKWebView alloc]initWithFrame:CGRectMake(0, 0, 300, 400)];
//
////      [self.view addSubview:webView];
//
////      [webView loadRequest:[NSURLRequest requestWithURL:[NSURL fileURLWithPath:path isDirectory:NO]]];
//
////// url    __NSCFString *    @"file:///Users/zhoubo5/jdflutter_webview/dart_2_js_web_example/build/web/index.html"    0x000060000263ec30
////      NSString *document = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
////
////  NSString *path = [document stringByAppendingString:@"/park.html"];
////
////      NSArray *LibraryArray =  NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
////
////      NSString *CachesPath = [[LibraryArray lastObject] stringByAppendingPathComponent:@"Caches"];
////
////      NSString *accessURLStr = [[[LibraryArray lastObject] stringByAppendingPathComponent:@"Caches"] stringByAppendingPathComponent:@"/web"];
////      NSURL *accessURL = [NSURL fileURLWithPath:accessURLStr];
////          [_webView loadFileURL:pathURL allowingReadAccessToURL:accessURL];
//
////      NSData *htmlData = [[NSData alloc] initWithContentsOfFile:@"/Users/zhoubo5/jdflutter_webview/dart_2_js_web_example/build/web/index.html"];
////            NSData *htmlData = [[NSData alloc] initWithContentsOfFile:path];
////
////      NSURL* nsUrl3 = [NSURL URLWithString:@"file:///Users/zhoubo5/Library/Developer/CoreSimulator/Devices/7FF29F20-5129-4931-8F79-A95C70CF2895/data/Containers/Data/Application/3DB61D34-D6DC-4CDB-BA2B-305775ECDDCE/Documents/web"];
//
////      if (@available(iOS 9.0, *)) {
////          [_webView loadData:htmlData MIMEType:@"text/html" characterEncodingName:@"UTF-8" baseURL:nsUrl3];
////      } else {
////          // Fallback on earlier versions
////      }
//
//      NSLog(@"zb....%@",@"loadFileURL");
//  }
//  return true;
//}