JIVE help says this:
"Accessing the Community From a Mobile Device"
Jive is accessible from mobile devices using the mobile Safari browser or by installing the Jive for iOS app from the Apple store onto an iPhone or iPad. For help using the iOS app, see the linked documentation.
The previous version of this was not pleasant. I have not tried the new version.
The browser shows fairly well without the app in the iPhone.
If you want particular message to be emailed to you, then "follow" to your Inbox and then set the email feature from "Preferences" under your avatar in the menu. Then you can reply-by-email. This works well enough for me on iPhone. You cannot see attachments in this email, but I can live with that and just go to the thread if necessary.
When answering via email, you are one tap away from opening the thread in Safari so you can always "tap over" when you need to check a screen shot or review more of the thread.
I find that posting to the forum via Safari is workable--a vast improvement over that awful system by RightNow that FileMaker Inc. used to use for one of the two communities that they then merged into the current system, but it's far from perfect. I have to pay very careful to the "suggested text" auto-correcting as it can do some very strange things to the text that I'm entering--especially if I've tapped delete a time or two to correct a typo.