From 7c9287543c7764fbb44082070350f56bd366f610 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Thu, 10 Jun 2021 10:33:24 -0400
Subject: [PATCH] Fix crash due to PencilKit undo manager not being available
 until viewDidAppear

---
 .../Compose/ComposeDrawingViewController.swift        | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/Tusker/Screens/Compose/ComposeDrawingViewController.swift b/Tusker/Screens/Compose/ComposeDrawingViewController.swift
index 29d89e7e..43005101 100644
--- a/Tusker/Screens/Compose/ComposeDrawingViewController.swift
+++ b/Tusker/Screens/Compose/ComposeDrawingViewController.swift
@@ -80,12 +80,13 @@ class ComposeDrawingViewController: UIViewController {
         
         updateLayout(for: toolPicker)
         canvasView.becomeFirstResponder()
+    }
+    
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
         
-        // wait until the next run loop iteration so that the canvas view has become first responder and it's undo manager exists
-        DispatchQueue.main.async {
-            NotificationCenter.default.addObserver(self, selector: #selector(self.updateUndoRedoButtonState), name: .NSUndoManagerDidUndoChange, object: self.undoManager!)
-            NotificationCenter.default.addObserver(self, selector: #selector(self.updateUndoRedoButtonState), name: .NSUndoManagerDidRedoChange, object: self.undoManager!)
-        }
+        NotificationCenter.default.addObserver(self, selector: #selector(self.updateUndoRedoButtonState), name: .NSUndoManagerDidUndoChange, object: self.undoManager!)
+        NotificationCenter.default.addObserver(self, selector: #selector(self.updateUndoRedoButtonState), name: .NSUndoManagerDidRedoChange, object: self.undoManager!)
     }
 
     func updateLayout(for toolPicker: PKToolPicker) {