how to start from scratch

To start from scratch in Xcode, you can follow these steps:

Disable Breakpoints: If you want to get back to the beginning without interruptions, disable all of your breakpoints with the breakpoint button in the debug bar. This allows you to continue without hitting breakpoints and then turn them back on to retrigger the problem.
Run Without Building: If your program is crashing and you need to relaunch it each time, use the command Control + R to run without building. This skips the build step and gets you immediately back to debugging. This is useful if you haven't changed your code and want to debug the old code one more time.
Navigating Xcode: If you're new to Xcode, familiarize yourself with the interface. The project navigator on the left-hand side shows your project's file hierarchy. You can use various navigators to get different perspectives of your project.
Creating New Files: You can create new files by right-clicking in the navigator. You can also use the option-drag method to copy existing files or use the clipboard to create new files with the contents of an existing file.

For more detailed guidance, you can refer to the session Xcode essentials.

These sessions provide a comprehensive overview of starting from scratch, debugging, and navigating Xcode effectively.