iOS: Unlike Android, the iPhone doesn't have app launchers that make it easy to find and load apps. Subsequently, you need to make use of workarounds to make shortcuts for your favourite apps from places other than the home screen. Push Launcher is an app that does that by adding your apps to your Notification Center.
With Push Launcher installed, you can add your favourite apps to your Notification Center so you can launch them from anywhere within iOS. Then, simply launch Push Launcher, and it will add a shortcut to your Notification Center.
It's not exactly the best way to launch apps, but it works within Apple's closed system.