HIja is a text-to-speech app and Action Extension for iOS that reads Klingon text out loud from any app. Just select the text you want to read, click "Share…", then select "HIja!" to hear your phrase. The container app provides a demo of the TTS functionality, with useful phrases like "Do you speak Federation Standard" and "I dont speak Klingon" pre-programmed, or write your own into the text field.
The TTS data in HIja is provided by DevID: https://github.com/De7vID