The resource could not be loaded because the App Transport Security policy requires the use of a secure connection.

问题

在根据《IOS开发指南 从helloworld到AppStore上架 第四版》学习的时候，看到第八章『树形导航结构』使用WKWebView进行三级导航展示详情，发现白屏

解决方案

WKWebView根据『WKNavigationDelegate』协议有几个方法，可以追踪加载进度

- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
    NSLog(@"准备加载页面");
}

- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation {
    NSLog(@"开始加载页面");
}

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    NSLog(@"已加载全部页面");
}

- (void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    NSLog(@"加载失败1");
}

- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    NSLog(@"加载失败2%@",error.userInfo);
}

重新执行后，发现进入了didFailProvisionalNavigation方法，这个时候我们打印error.code得到值为-1022。

2017-09-22 11:08:40.096041+0800 treeNavigation[6176:2793155] http://baike.baidu.com/view/3961.htm
2017-09-22 11:08:40.171849+0800 treeNavigation[6176:2793155] 准备加载页面
2017-09-22 11:08:40.184887+0800 treeNavigation[6176:2793155] 加载失败2{
    NSErrorFailingURLKey = "http://baike.baidu.com/view/3961.htm";
    NSErrorFailingURLStringKey = "http://baike.baidu.com/view/3961.htm";
    NSLocalizedDescription = "The resource could not be loaded because the App Transport Security policy requires the use of a secure connection.";
    NSUnderlyingError = "Error Domain=kCFErrorDomainCFNetwork Code=-1022 \"(null)\"";
    "_WKRecoveryAttempterErrorKey" = "<WKReloadFrameErrorRecoveryAttempter: 0x17403eae0>";
}

看到这里基本上就能猜到https的问题了，然后我们将url进行一次搜索替换，就可以了。

self.url = [self.url stringByReplacingOccurrencesOfString:@"http://" withString:@"https://"];