Now that iOS 9 was released in beta, a lot of developers are testing their apps to make sure everything is compatible. As part of iOS 9 Apple is including ATS, or App Transport Security.
The snippet from Apple is below, but the short version is that HTTPS w/TLS 1.2 is now enforced for apps.
App Transport Security
App Transport Security (ATS) enforces best practices in the secure connections between an app and its back end. ATS prevents accidental disclosure, provides secure default behavior, and is easy to adopt; it is also on by default in iOS 9 and OS X v10.11. 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. In addition, your communication through higher-level APIs needs to be encrypted using TLS version 1.2 with forward secrecy. If you try to make a connection that doesn't follow this requirement, an error is thrown. If your app needs to make a request to an insecure domain, you have to specify this domain in your app's
The interesting part is the requirement for forward secrecy, which requires ephemeral keys. If you are running any tests and this is failing, let me know.