func addStudent(_ student: Student) {

  concurrentStudentQueue.async(flags: .barrier) { 

self._students.append(student) 

DispatchQueue.main.async { //

  self.postContentAddedNotification()

}

  }

}

The code will ensure that the submitted DispatchWorkItem will be executed in parallel with any other DispatchWorkItem in the same queue.

GCD can dispatch a task

NSOperationQueue conforms to

GCD provides the following types of Queues:

'NSOperationQueue.mainQueue().addOperationWithBlock' will add the operation to

unowned reference types are declared as __

What is a trailing closure?

How could the following closure be rewritten to use shorthand arguments? s2 } ) >

How could you call the following function that takes a closure as an argument using trailing closure syntax: ()) { // function body goes here }>

Let’s assume "numbers" is an array of unsorted integers. Which of these could be used to sort numbers?

Choose the answer that declares an optional closure.