Choose the answer that declares an optional closure.

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

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

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

What is a trailing closure?

Which of the following statements is true regarding Swift closures and functions?

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

GCD provides the following types of Queues:

NSOperationQueue conforms to

GCD can dispatch a task

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.