Turning a concept into a working app that users can download from the App Store requires you to learn a new programming language, to develop the app using a proprietary tool and to submit it to Apple for review.
Learn Objective-C and Cocoa Touch
Developing your first iPhone or iPad app requires you to learn the Objective-C programming language. An evolution of the decades-old C language, you can use Objective-C to develop both iOS and Mac OS X apps.
In addition to Objective-C, developing an iOS app also requires you to learn Cocoa Touch, a software environment -- or framework -- that allows your Objective-C code to interact with an iPhone's hardware. While Objective-C works behind the scenes to perform such tasks as managing an app's internal database or keeping a tally of a character's life points in a game, Cocoa Touch handles all interactions with the device's hardware and interface, from using the built-in GPS chip to get a user's current location to responding to user interactions with the touch screen.
Similar to Windows' Visual Studio application, Apple has its own integrated development environment, named Xcode. This free program lets you create new app projects and write your Objective-C and Cocoa Touch code while providing you with hints and checking your code for errors.
Download the latest version of Xcode from the Mac App Store.
Enroll in the iOS Developer Program
While using Xcode is free, publishing an app or even installing it on your own iPhone for testing purposes requires you to enroll in Apple's iOS Developer Program and pay a yearly $99 subscription fee.
Test Your App
Testing your app is an important part of the development process, giving you a chance to find and eliminate bugs and therefore provide users with the best possible experience. While Xcode comes with an emulator that lets you test apps directly on your Mac, it is advisable to test your app on real-life devices as well to check how your code interacts with the iPhone's hardware.
Installing a test app on an iPhone requires you to have an active iOS Developer Program subscription and provision the app using Xcode.
Publish Your App
Using Xcode, submit your app to the iOS App Store and wait for Apple to review it. After an Apple employee has checked your app and determined it complies with the company's app quality and user interface guidelines, the company makes your app available for download from the App Store.