ios wkwebView 加载本地HTML css和Js 调用不成功 报错无法成功下载必要的资源

WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
         config.preferences = [[WKPreferences alloc] init];
         config.preferences.javaScriptEnabled = YES;
         config.preferences.javaScriptCanOpenWindowsAutomatically = YES;
         [config.preferences setValue:@(YES) forKey:@"allowFileAccessFromFileURLs"];//关键代码
         config.processPool = [[WKProcessPool alloc] init];
         WKUserContentController *con = [[WKUserContentController alloc] init];
         config.userContentController = con;
        _webview1 = [[WKWebView alloc] initWithFrame:window.bounds configuration:config];