Recently there was a very interesting discussion going on Twitter. The discussion was around if users preferred their apps to have dark theme or light theme. It was widely agreed that apps with dark theme are always preferred given that they can be used rather inconspicuously when in dark and also do not cause unnecessary strain on the eye. However, the entire of iOS 7 is based on light backgrounds and if you would like to darken that there is an option to invert colors in Accessibility. However, that would render a lot of pictures on your device waste, as a result a tweak called Eclipse is really useful.
Since the Tweak is available from Cydia store, you obviously must be running an iOS device that has been jailbroken and on iOS 7. Eclipse is a very simple jailbreak tweak that allow for an across the board dark theme being enabled for your iOS device. Not just the OS elements but the tweak also enables dark theme in all the third party applications. So, in case you use the official Twitter application, it would no more hurt your eyes with all the white in the background.
The results though are mixed and only the components that use common programmatic UI elements are affected. Some of the places such as the dialer or the messaging app are not darkened since they happen to use png images instead of programmatic UI. The tweak obviously hence require a lot of work from the developer including the option of only selectively darkening hand picked apps. Despite that, the tweak is rather useful and for only $.99 from Big Boss Repo is actually is a very useful add on to your device.