1. Introduction
Hello, this is Neil. In this article, I will show you how to get the source files of iOS 10 from .ipsw file. iOS 10 is released during WWDC this year. I believe that it is the best mobile operating systems on the market. I will not go into details about what’s new in iOS 10, you can find details here https://beta.apple.com/sp/betaprogram/
2. Download the restore image
In order to see the source files, you have to download the restore image, aka .ipsw file from the developer portal. You DON’T have to be a paid developer to do this. All you have to do is to enroll the Apple Developer Beta program which is FREE.
Here is the link: https://developer.apple.com/download/
Remember to choose the right configuration and select iOS restore images.
3. Unzipped, unpackaged
After the file is in the download folder, you should download a unarchiver (my favorite) https://itunes.apple.com/us/app/the-unarchiver/id425424353?mt=12 from the App Store on your Mac. Control click on the file and select Open With and select Other click Open
4. Inside the folder
After the file is unarchived, you will see a new folder created with a same name, open it and boom!! Here it is, iOS 10 source files. Here are several tips, info about the files inside the folder.
This is the inside 
Click and mont (open) the first .dmg file.
Here you can find almost all the files in the system. From ringtone to backgrounds to TouchID_Mach.framework. Other than this, you can also open system application folder and find executable files such as Maps and Messages. With little reverse engineering you can do some cool stuff with Apple system code. After all, use the resource responsibility. I hope you enjoy the article, please email me or leave a comment if you have any questions.
Credit:
Neil Nie 