how correctly use nwpathmonitor?

To correctly use NWPathMonitor, you would typically follow these steps:

1. Initialize the Monitor: Create an instance of NWPathMonitor. You can specify a specific interface type if you want to monitor a particular network interface, or use the default initializer to monitor all interfaces.

2. Set the Update Handler: Assign a closure to the pathUpdateHandler property of the monitor. This closure will be called whenever the network path changes. Inside this closure, you can check the status of the path (e.g., .satisfied, .unsatisfied, .requiresConnection) and take appropriate actions based on the network availability.

3. Start the Monitor: Call the start(queue:) method on the monitor, passing a DispatchQueue where the update handler will be executed. It's common to use a background queue for this.

4. Stop the Monitor: When you no longer need to monitor the network path, call the cancel() method on the monitor to stop it.

Here's a basic example in Swift:

import Network

let monitor = NWPathMonitor()

monitor.pathUpdateHandler = { path in
    if path.status == .satisfied {
        print("We're connected!")
    } else {
        print("No connection.")
    }
    
    print(path.isExpensive)
}

let queue = DispatchQueue.global(qos: .background)
monitor.start(queue: queue)

// To stop monitoring
// monitor.cancel()

This example sets up a network path monitor that prints a message whenever the network status changes, and it also checks if the connection is considered expensive (e.g., cellular data).

For more detailed information on debugging and logging, you might want to check out the session Run, Break, Inspect: Explore effective debugging in LLDB which covers various debugging techniques, including the use of breakpoints and logging.