Publish app in Appstore and send invitation through testflight and generate App Icons

Every app must provide an icon to be displayed on a device’s Homescreen and in the App Store. An app should specify several different icons of different dimensions to suit different screen sizes and different situations.

You can save valuable time by using Makeappicon.com to generate app icons

for publish follow this link 

https://www.youtube.com/watch?v=tnbOcpwJGa8

hiding tabbar at bottom with space in swift 3

self.tabBarController?.tabBar.isHidden = true

self.extendedLayoutIncludesOpaqueBars = true