Is it possible to synchronously wait for multiple tasks using GCD and continue after their completion?

Yes, GCD can be used to synchronously wait for the execution of multiple tasks and continue after their completion. Typically, DispatchGroup is used for this purpose. You add tasks to the group, start them asynchronously, and then call the wait() method on the group, which blocks the current thread until all tasks in the group are finished.

Example in Swift:

let group = DispatchGroup()

group.enter()
DispatchQueue.global().async {
    // Asynchronous task 1
    print("Task 1 started")
    sleep(2)
    print("Task 1 finished")
    group.leave()
}

group.enter()
DispatchQueue.global().async {
    // Asynchronous task 2
    print("Task 2 started")
    sleep(1)
    print("Task 2 finished")
    group.leave()
}

group.wait() // Wait for both tasks to complete
print("All tasks are finished")

Thus, you can synchronously wait for the execution of multiple asynchronous tasks.