Hi Daniel,
We are distributing Jabber for iPhone and iPad within the iTunes framework - have you checked out the following:
https://support.apple.com/en-us/HT201377
Please also note that we only support the latest version of Jabber - currently 11.0.3 as we are unable to address any issues that customers might encounter on older versions. As you may know, iOS 8 does not support iPhone 4 and in order to take advantage of significant improvements in iOS 8 Jabber no longer supports the iPhone 4.
Thanks,
Karin