iOS WKWebView 对 blob url 下载文件处理

处理类似  blob:https://XXX/ff8e66c5-b2f4-4070-8305

1.首先要拦截跳转把以blob开头的跳转链接转成WKNavigationActionPolicyDownload 代码如下，注意这个只能在iOS14.5以后才能使用

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler{
  if([navigationAction.request.URL.absoluteString hasPrefix:@"blob"]){
        if (@available(iOS 14.5, *)) {
            decisionHandler(WKNavigationActionPolicyDownload);
        } else {
            // Fallback on earlier versions
            decisionHandler(WKNavigationActionPolicyCancel);
        }
    }
    else{
        decisionHandler(WKNavigationActionPolicyAllow);
    }
}

2.然后实现代理方法

- (void)webView:(WKWebView *)webView navigationAction:(WKNavigationAction *)navigationAction didBecomeDownload:(WKDownload *)download API_AVAILABLE(ios(14.5)){
    download.delegate = self;// 遵守WKDownloadDelegate
}

3.最后实现WKDownloadDelegate代理

- (void)download:(WKDownload *)download decideDestinationUsingResponse:(NSURLResponse *)response suggestedFilename:(NSString *)suggestedFilename completionHandler:(void (^)(NSURL * _Nullable))completionHandler API_AVAILABLE(ios(14.5)){
    NSURL *temporaryDirectory = [NSFileManager.defaultManager temporaryDirectory];
    NSURL *url = [temporaryDirectory URLByAppendingPathComponent:suggestedFilename];
    completionHandler(url);
    
// url 是得到的文件URL路径（不是path路径）
//处理URL 就可以了
}