Swift is primarily used in the development of applications for which of the following platforms?

Swift is primarily used in the development of applications for iOS, which is Apple's mobile operating system. This programming language was created by Apple specifically for building applications within the Apple ecosystem, which includes not only iOS but also macOS, watchOS, and tvOS. Swift offers modern syntax, safety features, and performance improvements over its predecessor, Objective-C, making it a preferred choice for developers working on iPhone, iPad, and Apple Watch apps.

The other platforms mentioned—Windows, Linux, and Android—typically use different programming languages more suited to their respective ecosystems. For example, Windows development is commonly done using languages like C# and C++, Linux development often involves C and Python, and Android primarily utilizes Java and Kotlin. Thus, Swift's primary association with iOS development aligns with its design purpose and the environment for which it was intended.