Swift Call component from UIViewController in a UIView [duplicate] - ios

Question

This question already has answers here:
What does "Fatal error: Unexpectedly found nil while unwrapping an Optional value" mean?
(16 answers)
Closed 6 years ago.
I'm having a problem, I have a UIButton in a UIViewController class and I want to enable that button after an animation that happens in a UIView class that is in another file.
class MainViewController: UIViewController {
#IBOutlet weak var nextButton: UIButton!
#IBAction func nextButtonPressed(sender: UIButton) {
nextButton.enable = false
}
}
When I try to call the nextButton from the viewController class after the animation is done I get this error:
EXC_BAD_INSTRUCTION(code = EXC_I386_INVOP, subcode = 0x0)
I get the error on the line where I set the nextButton enable to true.
class CustomView: UIView {
var vc = MainViewController()
func animationEnded() {
vc.nextButton = true
}
}
I don't have a clue what I'm missing and I would appreciate some help. Thanks

Answer 1

You encounter an error because in your CustomView you create a new MainViewController, you're not using the one initialized from the storyboard. That new MainViewController doesn't have any of its properties initialized, so nextButton is nil, hence the crash when you try to access it.
What you want to do is notify your controller from the view that the animation has ended so that the controller can update the button (since the controller owns the button). The standard way to do this in Cocoa is to use the delegate pattern like so:
class MainViewController: UIViewController, CustomViewDelegate
{
#IBOutlet weak var nextButton: UIButton!
#IBOutlet weak var customView: CustomView!
#IBAction func nextButtonPressed(sender: UIButton) {
self.nextButton.enabled = false
}
override func awakeFromNib() {
super.awakeFromNib()
self.customView.delegate = self
}
func customViewAnimationDidEnd(customView: CustomView) {
self.nextButton.enabled = true
}
}
protocol CustomViewDelegate : class
{
func customViewAnimationDidEnd(customView: CustomView)
}
class CustomView: UIView
{
weak var delegate: CustomViewDelegate? = nil
func animationEnded() {
self.delegate?.customViewAnimationDidEnd(self)
}
}
In this implementation the controller is the view delegate and gets notified when interesting events happen in the view (like a particular animation ending).

Answer 2

Make a delegate in your UIView that tells when it should hapen
protocol CustomViewDelegate {
func pushThatButton()
}
in CustomView class put this:
weak var delegate: CustomViewDelegate?
then
func animationEnded() {
delegate.pushThatButton()
}
and in UIViewController
class MainViewController: UIViewController, CustomViewDelegate {
and implement delegate ofc
func pushThatButton()
nextButton.sendActionsForControlEvents(.TouchUpInside)
}
almost forget, do an outlet to your view in viewController and setup delegate! in viewDidLoad() or when you will find this best
customViewOutlet.delegate = self