iOS App Dev - iOS Programming - Building Mobile Application

Ios App Dev - iOS Programming - Building Mobile Application
Ios App Developer - Stanford University Developing IOS 7 Apps
https://www.youtube.com/watch?v=JNI2IHzGOyc

Learning C and Objective-C

If you have no programming experience and you want to write extensions/tweaks, you'll need to learn a lot about Objective-C and developing ordinary apps for iOS. (If you'd like to first try modifying code in simple ways to explore some possibilities, you can try the paid package Flex, on the BigBoss repository in Cydia.)
To give you a taste, Code School has an iOS programming course for beginners, with a free interactive guide to getting started with Objective-C. You can also try the free courses offered by Codecademy - they're not about Objective-C or iOS, but they can give you a general sense of what programming is like.
For further study:
Apple's developer documentation - see the Xcode page and Start Developing iOS Apps Today.
Videos: Stanford's "Developing iOS 7 Apps for iPhone and iPad" class on iTunes U and The New Boston video tutorials. There are more recommendations for videos and blogs in this list from CodeMentor.
Books: Programming in Objective-C by Stephen G. Kochan, Objective-C Programming: The Big Nerd Ranch Guide by Aaron Hillegass, and iOS Programming: The Big Nerd Ranch Guide by Aaron Hillegass, Joe Conway, and Christian Keur.
Forums: unofficial iPhone Dev SDK forum and Stack Overflow.
It's good to learn some C too; it'll give you a better foundation for learning Objective-C. You'll want to know about pointer arithmetic, the Objective-C runtime, buffer overflows, bitwise operations, the model-view-controller pattern, etc.
Ideally you'll get to a point where you're comfortable writing and running code for iOS. If you're already there, definitely keep reading!

iOS Swift 1: Creating a Hello World App
https://www.youtube.com/watch?v=N-GNV7jhKV4
iOS Development: How to Start to Learn to Develop iOS Apps. Myths about How to Become iOS Developer
https://www.youtube.com/watch?v=lsw_IdUgvOk

Setting up Theos

Follow Theos/Setup to set up your Theos environment by installing Theos and creating your first project. These links may also be helpful: guide on Stack Overflow, this Theos documentation by theiostream, and Theos Install Script.
You'll probably also want to read more about Cydia Substrate - see saurik's Substrate documentation.
Finding example projects

Here is a list of just a few of the many open source projects that can be used as examples: Open Source Projects.
For some simple example projects you can build with Theos, see codyd51's Theos Examples.
Not finding what you are looking for? Try searching through GitHub for iOS Tweaks with a simple trick, "extension:xm".
Example:
extension:xm SBAwayController
Using the above code will search GitHub for all files with the extension .xm (because Theos by default creates a Tweak.xm file when creating a new tweak). The example above will result in finding tweaks that reference SBAwayController. Not all developers use the .xm file extension, but a large number do, and this will help you in finding those examples.