Does a concept of Run Loop exist for the global thread in the system?

In iOS, there is a concept called Run Loop, which manages event processing and timers in a thread. For the main thread, the system automatically creates and starts a Run Loop, ensuring the handling of user events, UI updates, and other tasks.

For global (background) threads, a Run Loop is not created automatically. If a Run Loop is needed in a background thread (for example, to handle events or timers), it must be created and started manually. Thus, a global thread does not have an automatically running Run Loop, unlike the main thread.

Example of creating and starting a Run Loop in a background thread:

let thread = Thread {
    let runLoop = RunLoop.current
    runLoop.add(Port(), forMode: .default)
    runLoop.run()
}
thread.start()

In summary: the concept of Run Loop exists for any thread, but for a global (background) thread, it is not started automatically by the system and requires explicit creation and starting.