App Transport Security (ATS) lets an app add a declaration to its Info.plist file that specifies the domains with which it needs secure communication. ATS prevents accidental disclosure, provides secure default behavior, and is easy to adopt. You should adopt ATS as soon as possible, regardless of whether you’re creating a new app or updating an existing one.
If you’re developing a new app, you should use HTTPS exclusively. If you have an existing app, you should use HTTPS as much as you can right now, and create a plan for migrating the rest of your app as soon as possible.
When you build your app and see the message like
Application Transport Security has blocked a cleartext HTTP (http://) resource load since it is insecure. Temporary exceptions can be configured via your app's Info.plist file.
It might be your code may use http://hostname/xxx connection. To duisable ATS, add the following into info.plist .