使用 WKWebView 遇到的一些问题

1 .前端 target="_blank" 设置后无法加载页面 和 window.open(url) 无法打开新页面
原因：两者都是要在新窗口打开，判断下当前请求的targetFrame是不是MainFrame，不是则要在主动加载链接
解决办法：

- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures {
    
    // 修复_blank的bug
    if (!navigationAction.targetFrame.isMainFrame) {
        
        [webView loadRequest:navigationAction.request];
    }
    
    return nil;
}

2. WKWebView 加载本地资源
   2.1 loadFileURL 的同级文件目录
   通过allowingReadAccessToURL 参数传入需要访问的目录

NSURL * accessUrl = [NSURL fileURLWithPath:cacheDirPath()];
    [self.webView loadFileURL:urlComponents.URL allowingReadAccessToURL:accessUrl];

2.2 loadHTMLString加载本地文件

• 测试baseURL 传入 [NSBundle mainBundle] 中的文件可以正常访问
• 动态创建的文件访问只能放在 NSTemporaryDirectory() 目录下才能访问（其它目录在模拟器访问没问题、真机访问不了）

NSURL * baseURL = [NSURL fileURLWithPath:NSTemporaryDirectory() isDirectory:YES];
        [_web loadHTMLString:kRichEditorInitHtml baseURL:baseURL];

3.链接后边拼接url参数前端接收不到

//UIWebView经常这样拼接
[self loadUrl:[NSString stringWithFormat:@"%@?showvoice=%@",[self templatePath],[Global showvoice]]];

解决方案：使用NSURLComponents

    NSURL *fileUrl = [NSURL fileURLWithPath:[self templatePath] isDirectory:NO];//此部分没有?所以没有问题，isDirectory=YES会导致多一层目录。
    NSURLComponents *urlComponents = [NSURLComponents componentsWithURL:fileUrl resolvingAgainstBaseURL:NO];
    [urlComponents setQueryItems:@[
        [NSURLQueryItem queryItemWithName:@"showvoice" value:[Global showvoice]]
    ]];
    NSLog(@"urlComponentsURL:%@",urlComponents.URL);
    NSURL * accessUrl = [NSURL fileURLWithPath:cacheDirPath()];
    [self.webView loadFileURL:urlComponents.URL allowingReadAccessToURL:accessUrl];

4.前端alter 弹出窗不弹出
解决：实现WKUIDelegate 的几个方法

// 显示一个按钮。点击后调用completionHandler回调
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler{
    
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:message message:nil preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {

        completionHandler();
    }]];
    [self presentViewController:alertController animated:YES completion:nil];
}

// 显示两个按钮，通过completionHandler回调判断用户点击的确定还是取消按钮
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler{
    
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:message message:nil preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        completionHandler(YES);
    }]];
    [alertController addAction:[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        
        completionHandler(NO);
    }]];
    [self presentViewController:alertController animated:YES completion:nil];
    
}

// 显示一个带有输入框和一个确定按钮的，通过completionHandler回调用户输入的内容
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * _Nullable))completionHandler{
    
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"" message:nil preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
        
    }];
    [alertController addAction:[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        completionHandler(alertController.textFields.lastObject.text);
    }]];
    [self presentViewController:alertController animated:YES completion:nil];
}