The Cydia Tweak Mirmir has been officially released and works with devices that have iOS 8 or higher. Mirmir cydia tweak provides you the facility to have true side by side windowed multitasking on jailbroken devices including iPhone and iPads that are running iOS 8.3 or 8.4. Users can resize the app windows, move them around as well as rotate them if they want to use the app in landscape mode. From settings, that can be accessed through the dedicated homescreen icon, you can select activation method, default orientation as well as set a default minimum and maximum size for the window.
Mirmir also supports Activator so you can assign gestures for maximizing or minimizing the window, closing all or the current window, changing the window orientation and much more. After you have installed this tweak, you will be able to configure it to your own personal preferences in the Settings app.
If you are interested, then you can download Mirmir iOS 8 from the BigBoss repository in Cydia just $3.99. To install this program requires a jailbroken device (see if and how you can do the jailbreak to your iPhone by clicking here) and you need an Internet connection to download the package. This tweak is compatible with iOS 8.0 and later versions of the mobile operating system from Apple.