1.首先排查
原来apple-app-site-association文件是放到根目录下，但是现在要求放到
.well-known目录下
https://<fully qualified domain>/.well-known/apple-app-site-association
并且域名不能重定向
You must host the file using https:// with a valid certificate and with no redirects.
https://developer.apple.com/documentation/safariservices/supporting_associated_domains
2.在ios13之前的设备可以通过universal link打开app，但是ios14不能打开了
原因是在ios13访问apple-app-site-association文件是通过设备去访问的，ios14之后是由apple的服务器区去访问。我们的问题是设备在本地网络下能访问到apple-app-site-association文件，但是苹果服务器访问走的是海外网络，ssl证书有问题导致不能访问到apple-app-site-association文件。修改这个问题之后就能顺利的打开app了。
Starting with macOS 11 and iOS 14, apps no longer send requests for apple-app-site-association files directly to your web server. Instead, they send these requests to an Apple-managed content delivery network (CDN) dedicated to associated domains.
While you’re developing your app, if your web server is unreachable from the public internet, you can use the alternate mode feature to bypass the CDN and connect directly to your private domain.
