Whether you are looking to replace the stock App Switcher or want to have something to go with it, Phenomenon tweak is a tweak you should try. This app switcher replacement tweak can be invoked by force tapping on the left side of the screen (iPhone 6s and 6s Plus) or using an Activator gesture that you can choose from settings. In addition to that Phenomenon also allows users to access the new multitasking interface by double tapping on the menu.
The tweak offers a number of features in addition to offering an alternative way of switching apps. This includes the ability to close all switcher apps by long pressing or force tapping on an app card. Users also get to configure Phenomenon to vibrate the device whenever it is invoked, which gives a nice feel when using the tweak on the iPhone. Phenomenon also gives users the ability to choose between a smaller Control Center and the normal Control Center.
You can download the Phenomenon tweak from Cydia for $2.99.