Weak vs Unowned for non-optional delegates

Question

If my viewcontroller must be initialized with a delegate, is there any danger at all to doing using an unowned instead?

Using weak seems to introduce the probability of functions failing (see below), although it will not crash.

Would using unowned in this case be unsafe in anyway?

class MyViewController: UIViewController
  private weak var delegate: MyViewControllerDelegate?
  init(delegate: MyViewControllerDelegat) {
    self.delegate = delegate
  }
  func foobar {
    delegate??
  }

compared to

class MyViewController: UIViewController
  private unowned var delegate: MyViewControllerDelegate
  init(delegate: MyViewControllerDelegate) {
    self.delegate = delegate
  }
  func foobar {
    delegate.doAction()
  }

Answer 1

If your controller must be initialized with a delegate and the controller cannot work without it then unowned is the correct solution. However, you have to make sure that the delegate is never deallocated before your controller is deallocated. Typically, the delegate should be the owner of your controller.

However, using weak is not complicated either:

delegate?.doAction()