Fix safe area on Compose screen not including keyboard on iOS 13

Tusker/Screens/Compose/ComposeHostingController.swift

@@ -21,6 +21,9 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
     
     private var cancellables = [AnyCancellable]()
     
+    private var keyboardHeight: CGFloat = 0
+    private var toolbarHeight: CGFloat = 44
+    
     private var mainToolbar: UIToolbar!
     private var inputAccessoryToolbar: UIToolbar!
     private var visibilityBarButtonItems = [UIBarButtonItem]()
@@ -54,7 +57,7 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidHide(_:)), name: UIResponder.keyboardDidHideNotification, object: nil)
         
         // add the height of the toolbar itself to the bottom of the safe area so content inside SwiftUI ScrollView doesn't underflow it
-        additionalSafeAreaInsets = UIEdgeInsets(top: 0, left: 0, bottom: 44, right: 0)
+        updateAdditionalSafeAreaInsets()
         
         pasteConfiguration = UIPasteConfiguration(forAccepting: CompositionAttachment.self)
         
@@ -125,6 +128,9 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         return toolbar
     }
     
+    private func updateAdditionalSafeAreaInsets() {
+        additionalSafeAreaInsets = UIEdgeInsets(top: 0, left: 0, bottom: toolbarHeight + keyboardHeight, right: 0)
+    }
     
     @objc private func keyboardWillShow(_ notification: Foundation.Notification) {
         keyboardWillShow(accessoryView: inputAccessoryToolbar, notification: notification)
@@ -135,6 +141,17 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         
         accessoryView.alpha = 1
         accessoryView.isHidden = false
+        
+        // on iOS 14, SwiftUI safe area automatically includes the keyboard
+        if #available(iOS 14.0, *) {
+        } else {
+            let userInfo = notification.userInfo!
+            let frame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as! CGRect
+            // temporarily reset add'l safe area insets so we can access the default inset
+            additionalSafeAreaInsets = .zero
+            keyboardHeight = frame.height - view.safeAreaInsets.bottom - accessoryView.frame.height
+            updateAdditionalSafeAreaInsets()
+        }
     }
     
     @objc private func keyboardWillHide(_ notification: Foundation.Notification) {
@@ -167,6 +184,13 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         } completion: { (finished) in
             accessoryView.alpha = 1
         }
+        
+        // on iOS 14, SwiftUI safe area automatically includes the keyboard
+        if #available(iOS 14.0, *) {
+        } else {
+            keyboardHeight = 0
+            updateAdditionalSafeAreaInsets()
+        }
     }
     
     @objc private func keyboardDidHide(_ notification: Foundation.Notification) {
@@ -242,17 +266,6 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
     
 }
 
-extension ComposeHostingController {
-    struct EnvironmentWrappingView<Content: View, EnvironmentObject: ObservableObject>: View {
-        let content: Content
-        let environmentObject: EnvironmentObject
-        
-        var body: some View {
-            content.environmentObject(environmentObject)
-        }
-    }
-}
-
 extension ComposeHostingController: ComposeUIStateDelegate {
     var assetPickerDelegate: AssetPickerViewControllerDelegate? { self }