You can install Cydia 1.1.23 on iOS 8.4 device, as per reports say that Cydia has just received another major update in version 1.1.23. It brought in some of the most requested new features along with bug fixes.
Let's talk about new feature in details. With Cydia 1.1.23, you can now not only downgrade packages to the last stable release with ease, but also to any previous version of the same package as long as it is available in the repository.
So as you understood whenever an update to a tweak causes issues, you can simply downgrade back to the older version by clicking on Modify->Downgrade from the tweakєі page on Cydia.
The Second major feature that was added to Cydia is tweaks discovery feature which is actually inspired by TweakHub. From now on the front Cydia page, you will find a new option for “Find Extensions for Applications”. This option will basically present you a categorized list of all the possible Cydia Substrate based tweaks available in Cydia to customize or enhance the stock or App Store apps installed on your iPhone or iPad.
According to users reports when their system cache was cleared, Cydia would stop running. This last Cydia update fixes this issue.
To install Cydia 1.1.23 on iOS 8.4 device already jailbroken, just open Cydia, click on Changes tab and push Refresh button (you can find it on the top left corner). Then please wait for the packages to reload. Once packages are refreshed, search for Cydia Installer package and update to version 1.1.23.
Alternatively if Cydia prompts you with “Essential Upgrade” message on initial load, you can simply click on “Complete Upgrade” to upgrade your device to the Cydia latest version.
As you may notice currently saurik is taking a very Apple-like approach with Cydia. He allows developers to modify Cydia, and picks the parts that best work and incorporates them into Cydia directly.