How IOS apps Add splash screen and app app icons

In iOS development often to add a splash screen for the project, the purpose of the main two: first, more beautiful, second, in the Start screen rendering while loading the initialization of the internal project data.
Note in iOS development, the need is a PNG format picture, only good support for this format, money is wayward.
The following are all supported applications in IOS7 and above:
Preparatory work:
PNG images of 1242*2208, 750*1334 pixels mainly distinguish between 5.5-inch and 4.7-inch iphone (iOS8 and above systems) that support the normal vertical screen state of the retina screen.
2208*1242 pixel PNG image main distinguish 5.5-inch iphone (iOS8 and above system) that supports the horizontal screen state of retina screen
640*960, 640*1136 pixels png images mainly distinguish 4-inch mobile phones (iOS7 and above) that support normal vertical screen status of retina screens.
768*1024, 1536*2048 pixel PNG images primarily distinguish ipad (iOS7 and above) that supports normal vertical screen status on retina screens
1024x768, 2048*1536 pixels of PNG images mainly distinguish the ipad (iOS7 and above) that supports the horizontal screen state of the retina screen.
The default state, the status time of the splash screen is 1s, if you want to extend the time:
In XXXAPPDELEGATE.M-(BOOL) Application: (uiapplication ) application didfinishlaunchingwithoptions: (NSDictionary Insert the following line of code into the Launchoptions method:
[Nsthread sleepfortimeinterval:5.0];//because by default the welcome interface time is only one second, plus this sentence is to extend
Not finished, to be continued ...

How IOS apps Add splash screen and app app icons