iOS, which was previously called iPhone OS, is a mobile operating system developed by Apple Inc. Its first release was in 2007, which included iPhone and iPod Touch. iPad (1st Generation) was released in April 2010 and iPad Mini was released in November 2012.
The iOS devices get evolved quite frequently and from experience, we find that at least one version of iPhone and iPad is launched every year. Now, we have iphone5 launched which has its predecessors starting from iPhone, iPhone 3gs, iPhone 4, iPhone 4s. Similarly, iPad has evolved from iPad (1st Generation) to iPad (4th Generation) and an additional iPad Mini version.
The iOS SDK has evolved from 1.0 to 6.0. iOS 6.0, the latest SDK is the only officially supported version in Xcode 4.5 and higher. We have a rich Apple documentation and we can find which methods and libraries can be used based on our deployment target. In the current version of Xcode, we’ll be able to choose between deployment targets of iOS 4.3, 5.0 and 6.0.
The power of iOS can be felt with some of the following features provided as a part of the device.
The number of users using iPhone/iPad has increased a great deal. This creates the opportunity for developers to make money by creating applications for iPhone and iPad the Apple's App Store.
For some one new to iOS, Apple has designed an application store where the user can buy apps developed for their iOS devices. A developer can create both free and paid apps to App Store. To develop applications and distribute to the store, the developer will require to register with iOS developer program which costs $99 a year and a Mac with Mountain Lion or higher for its development with latest Xcode.