Попробуйте с:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSExceptionDomains</key>
<dict>
<key>domain.com</key>
<dict>
<!--Include to allow subdomains-->
<key>NSIncludesSubdomains</key>
<true/>
<!--Include to allow HTTP requests-->
<key>NSTemporaryExceptionAllowsInsecureHTTPLoads</key>
<true/>
<!--Include to specify minimum TLS version-->
<key>NSTemporaryExceptionMinimumTLSVersion</key>
<string>TLSv1.1</string>
</dict>
</dict>
</dict>
Для блокировки всех HTTP попробуйте
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<false/>
<key>NSExceptionDomains</key>
<dict>
<key>*</key>
<dict>
<key>NSExceptionAllowsInsecureHTTPLoads</key>
<false/>
</dict>
</dict>
</dict>