sorry, i accidently clicked the "best answer" link within my own question, so i could not add this information to the correct question, however i think this might be of interest to everyone

i found that it's not possible to send an sms with predefined text, as it's not possible in the Apple SDK either. while some private methods do exist in the native sdk, which could enable this feature, using them will mean that your app will be rejected by apple when submitting it to the app store