WebView 中图片长按出现弹框，点击存储图像闪退的解决方案

　　在使用 WKWebView 展示 H5 时，如果 H5 中有图片，长按图片会出现弹框，在 iOS11 系统中，存储图像，如果未开启相册权限，会直接 Crash 掉：

　　解决方案一（原生解决）：　　

　　在代理方法中添加如下代码，禁掉弹框：

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    NSLog(@"webViewDidFinishLoad");
    [self.webView evaluateJavaScript:@"document.documentElement.style.webkitTouchCallout='none';" completionHandler:nil];
    [self.webView evaluateJavaScript:@"document.documentElement.style.webkitUserSelect='none';"completionHandler:nil];
}

　　另一种：

// 禁止选择CSS
        NSString *css = @"body{-webkit-user-select:none;-webkit-user-drag:none;}";
        // CSS选中样式取消
        NSMutableString *javascript = [NSMutableString string];
        [javascript appendString:@"var style = document.createElement('style');"];
        [javascript appendString:@"style.type = 'text/css';"];
        [javascript appendFormat:@"var cssContent = document.createTextNode('%@');", css];
        [javascript appendString:@"style.appendChild(cssContent);"];
        [javascript appendString:@"document.body.appendChild(style);"];
        // javascript注入
        WKUserScript *noneSelectScript = [[WKUserScript alloc] initWithSource:javascript injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
        WKUserContentController *userContentController = [[WKUserContentController alloc] init];
        [userContentController addUserScript:noneSelectScript];
        WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
        configuration.userContentController = userContentController;
        CGRect frame = CGRectMake(0, 0, kScreenWidth, kScreenHeight - 44.f -20.f);
        WKWebView *webView = [[WKWebView alloc] initWithFrame:frame configuration:configuration];
        NSURLRequest* request = [NSURLRequest requestWithURL:_brandInfoURL];
        [webView loadRequest:request];
        _webView = webView;
        [self.view addSubview:webView];

　　解决方案二（H5）解决：

img { pointer-events: none; }