Break temporary retain cycle in system presentation style (#40)

By retaining the entire `context` in the captured observer closure, we're implicitly capturing the `context.presenting` `UIViewController` for the duration of the transition until the `DismissalTransitionDidEndNotification` notification is fired.

If the `DismissalTransitionDidEndNotification` is never triggered, e.g. in the case of early deallocation following presentation, this could lead to the presenting view controller being retained indefinitely.

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   in specific scenarios.
 - Fixed an issue where the `accessibilityAlignment` property of `HGroup` was not being respected.
 - Fixed an issue where `accessibilityAlignment` and `horizontalAlignment` would overwrite one another
+- Break a temporary retain cycle in `.system` presentation style
 
 ### Changed
 - `CollectionViewConfiguration.usesBatchUpdatesForAllReloads` now defaults to `true`.

Sources/EpoxyPresentations/PresentationModel.swift

@@ -290,10 +290,10 @@ extension PresentationModel.Presentation {
             forName: .init("\(UIPresentationController.self)DismissalTransitionDidEndNotification"),
             object: presented,
             queue: .main,
-            using: { _ in
+            using: { [didDismiss = context.didDismiss] _ in
               guard token != nil else { return }
               token = nil
-              context.didDismiss()
+              didDismiss()
             })
 
         context.presenting.present(