Correctly display FAB in post screen on iPad split screen mode (#18609)

Author: mokagio

RELEASE-NOTES.txt

@@ -13,6 +13,7 @@
 * [*] Block Editor: Gallery block: Fix broken "Link To" settings and add "Image Size" settings [https://github.com/wordpress-mobile/gutenberg-mobile/pull/4841]
 * [*] Block Editor: Unsupported Block Editor: Prevent WordPress.com tour banner from displaying. [https://github.com/wordpress-mobile/gutenberg-mobile/pull/4820]
 * [*] Widgets: we fixed an issue where text appeared flipped in rtl languages [#18567]
+* [*] Posts list: we fixed an issue where the create button was not shown on iPad in split screen [#18609]
 
 19.8
 -----

WordPress/Classes/ViewRelated/Post/PostListViewController.swift

@@ -174,6 +174,7 @@ class PostListViewController: AbstractPostListViewController, UIViewControllerRe
         configureNavigationButtons()
 
         configureInitialFilterIfNeeded()
+        listenForAppComingToForeground()
 
         createButtonCoordinator.add(to: view, trailingAnchor: view.safeAreaLayoutGuide.trailingAnchor, bottomAnchor: view.safeAreaLayoutGuide.bottomAnchor)
     }
@@ -212,6 +213,12 @@ class PostListViewController: AbstractPostListViewController, UIViewControllerRe
 
     override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
         super.traitCollectionDidChange(previousTraitCollection)
+        toggleCreateButton()
+    }
+
+    /// Shows/hides the create button based on the trait collection horizontal size class
+    @objc
+    private func toggleCreateButton() {
         if traitCollection.horizontalSizeClass == .compact {
             createButtonCoordinator.showCreateButton(for: blog)
         } else {
@@ -379,6 +386,13 @@ class PostListViewController: AbstractPostListViewController, UIViewControllerRe
         filterSettings.setFilterWithPostStatus(initialFilterWithPostStatus)
     }
 
+    /// Listens for the app coming to foreground in order to properly set the create button
+    private func listenForAppComingToForeground() {
+        NotificationCenter.default.addObserver(self,
+                                               selector: #selector(toggleCreateButton),
+                                               name: UIApplication.willEnterForegroundNotification,
+                                               object: nil)
+    }
     // Mark - Layout Methods
 
     override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {