1. Xcode Debugger: The Xcode debugger is the most popular debugging tool for Swift development. It can be used to debug both iOS and macOS apps, and provides a graphical interface to view and edit variables, and step through code.
2. LLDB: LLDB is a command-line debugger for Swift development. It can be used to debug both iOS and macOS apps, and provides a powerful set of commands to view and edit variables, and step through code.
3. Instruments: Instruments is a performance-analysis tool for Swift development. It can be used to analyze the performance of an iOS or macOS app, and provides graphical tools to identify bottlenecks and memory leaks.
4. Swift REPL: The Swift REPL (Read-Evaluate-Print-Loop) is an interactive command-line tool for Swift development. It can be used to quickly test code snippets, and provides a powerful set of commands to view and edit variables, and step through code.