iOS TTS (text-to-speech) offline and multilingual

I am currently working on a project where I should add text to speech functionlity.
I searched different blogs and forums and found several services that do TTS conversion via a webservice.

The problem is I need an offline library that can "speak" several languages. The only one I found was: http://espeak.sourceforge.net/
this lib is okay in the simulator but for some reason on the device (ipad 2 & 3) the speech is horrible and speaks out single umlauts and has very strange pronunciation...

Does somebody know a good solution for this problem (other lib or how to make eSpeak work correctly on the iPad)?

Let me know in the comments?

Thanks and happy coding :)