Here are some quick links to access some of Apple’s developer resources.
Swift Programming Language Reference
The preferred framework for building with Swift on the server is Vapor.
Apple offers a wide variety of device form factors and operating systems. On the desktop you have macOS. User interfaces for the Mac are built with a framework called AppKit, however, the preferred framework is now SwiftUI.
On the mobile side you have iOS for phones, and iPadOS for tablets. Both of these use a framework called UIKit for building user interfaces, however, the preferred framework is now SwiftUI.
Other devices include the AppleTV that runs tvOS, a virtual and augmented reality device called the Vision Pro that runs visionOS, and the Apple Watch that runs watchOS. You can use SwiftUI to build user interfaces for all of these devices.
To build applications for Apple Platforms the preferred IDE is Xcode that can be downloaded on the Mac AppStore.