iOS 9 forces connections that are using HTTPS to be TLS 1.2 to avoid recent vulnerabilities. In iOS 8 even unencrypted HTTP connections were supported, so that older versions of TLS didn’t make any problems either. As a workaround, you can add this code snippet to your Info.plist:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>
Thereby you’re disabling the App Transport Security. Hope that’s helpful.