ScreenAction

A type of container that the action uses for navigation.

The type of value returned by the action.

Alias for the closure that is called after the action is completed.

Casts the instance to the specified type if it’s possible to do so.

This method is useful for casting instances of the AnyScreenAction type, because the standard as and is operators are unusable for them. For example, you can’t do something like this:

let anyAction = ScreenDismissAction<UIViewController>().eraseToAnyScreen()

if let dismissAction = anyAction as? ScreenDismissAction<UIViewController> {
    print(dismissAction.animated)
}

The compiler will issue the following warning:

Cast from 'AnyScreenAction<UIViewController, Void>'
to unrelated type 'ScreenDismissAction<UIViewController>()' always fails

In this case, you can use the cast(to:) method instead:

if let dismissAction = anyAction.cast(to: ScreenDismissAction<UIViewController>.self) {
    print(dismissAction.animated)
}

Default implementation uses standard type casting. You don’t need to implement this method yourself.

Сombines this action with another.

Some navigation actions can be combined with others to form a single new action that does the same thing. For example, you need to push two view controllers into the navigation stack, this can be done by two calls to the pushViewController(_:animated:) method:

navigationController.pushViewController(firstViewController, animated: true)
navigationController.pushViewController(secondViewController, animated: true)

But such a transition will be ugly. It is better to combine two push actions into single call to the setViewControllers(_:animated:) method:

navigationController.setViewControllers([firstViewController, secondViewController], animated: true)

You can implement combining such navigation actions in this method. Use the cast(to:) method to check the type of navigation action from the other parameter and return nil if the actions cannot be combined:

guard let other = other.cast(to: SomeAction.self) else {
    return nil
}

Default implementation returns nil.

Performs action in the screen container.

Wraps this action with a type eraser.

Use eraseToAnyAction() to expose an instance of AnyScreenAction, rather than this action’s actual type. This form of type erasure preserves abstraction across API boundaries, such as different modules. When you expose your actions as the AnyScreenAction type, you can change the underlying implementation over time without affecting existing clients.

Wraps this action with a type eraser, ignoring the output type of the action.

Use eraseToAnyVoidAction() to expose an instance of AnyScreenAction, rather than this action’s actual type. This form of type erasure preserves abstraction across API boundaries, such as different modules. When you expose your actions as the AnyScreenAction type, you can change the underlying implementation over time without affecting existing clients.