Although iOS only accounts for about 18% of the market share, it is arguably the more dominant of the two major platforms. iOS is owned and managed by Apple, the company most responsible for bringing mobile computing into the mainstream with the advent of iPhone and iPad technologies.
The reason that iOS doesn’t extend to as many devices as Android is that it is not open source—iOS operates exclusively on Apple products. Likewise, to build applications for iOS, developers need to use a Mac computer running OS X (the standard Mac operating system).
Apple also provides native tools and libraries for mobile development, and developers are encouraged to use Apple’s Swift programming language.
Because Apple keeps such tight control over the hardware and software aspects of iOS development, iOS performance is usually very responsive, stable, and easy to use. Device fragmentation is also less of a concern because Apple allows its applications to run only on its own proprietary hardware. On the other hand, stricter guidelines mean that it can be more difficult to create fully customised apps, and any new iOS applications must be submitted to the App Store for review and approval.