In Swift, a DispatchGroup is a way to group together multiple tasks and track when they all complete. You can use a Dispatchgroup to submit multiple tasks to a dispatch queue at the same time, and then use the group to wait for all of the tasks to finish before continuing. Here’s an example of how you might use a dispatch group in Swift:

let dispatchGroup = DispatchGroup()

dispatchGroup.enter()
DispatchQueue.global().async {
    // Perform task 1
    dispatchGroup.leave()
}

dispatchGroup.enter()
DispatchQueue.global().async {
    // Perform task 2
    dispatchGroup.leave()
}

dispatchGroup.wait()

// All tasks are complete

In this example, we create a dispatch group and then use the enter() method to indicate that a task has been added to the group. We then perform the task asynchronously on a background queue, and when the task is complete, we use the leave() method to indicate that the task has finished.

After all of the tasks have been added to the group, we can use the wait() method to block the current thread until all tasks in the group have completed. This can be useful if you want to perform some action after all of the tasks are finished, such as updating the UI or writing to a file.

You can also use the notify(queue:execute:) method to specify a block of code to be executed when all tasks in the group have completed, rather than using the wait() method to block the current thread.

let dispatchGroup = DispatchGroup()

dispatchGroup.enter()
DispatchQueue.global().async {
    // Perform task 1
    dispatchGroup.leave()
}

dispatchGroup.enter()
DispatchQueue.global().async {
    // Perform task 2
    dispatchGroup.leave()
}

dispatchGroup.notify(queue: .main) {
    // All tasks are complete
}

In this example, the block of code passed to notify(queue:execute:) will be executed on the main queue when all tasks in the group have completed.