在 swift 中获取 viewController.view 的呈现视图控制器

Question

i am trying to get the presenting viewController of a viewController's view The idea is like that : i have a

viewController = CategoriesViewController

and i am presenting its view inside anther

viewController = HomeViewController

by using

CategoriesViewController.view so when i want to reach the

HomeViewController from CategoriesViewController

i do this

let vc = self.presentingViewController as? HomeViewController

but it is telling me that it is nil i tried the

.parentViewController

and it is returning

CategoriesViewController

Answer 1

In case you want to change a variable in HomeVieController using CategoriesViewController you could create your own protocol . You can use protocols to communicate between different controllers.

    protocol ChangeVariableProtocol {
            func changeVar(variable: Int)
        }

In the protocol itself you only declare methods. In your CategoriesViewController you would create a delegate Varibale like this

var changeVarDelegate: ChangeVariableProtocl?

Whenever you want to change the variable in CategoriesViewController you call your protocol method.

changeVarDelegate?.changeVar(10)

In HomeViewController you need to implement this protocol and initialize the changeVarDelegate variable.

    extension HomeViewController: ChangeVarProtocol {
        func changeVar(var: variable) {
           // Implement your own logic here
         self.valueToChange = variable
        }

And make sure that you initialize changeVarDelegate when you are instancing your CategoriesViewController .

Hope this helps!

Answer 2

• Create a callback closure property both in CategoriesViewController and in its view.
• Right before presenting the controller assign the closure to change the value of a property to the callback property in the controller.
• In viewDidLoad hand the closure over to the view.
• Call the closure in the view to be executed in the presenting controller.