From fc7cff333ece1ff4ed19ed158dcd66db1d5c609a Mon Sep 17 00:00:00 2001
From: Michael Schneider <mischneider1@gmail.com>
Date: Sun, 19 Jun 2016 14:59:39 -0700
Subject: [PATCH] Prevent subclassing of ASTextNode and ASImageNode

---
 AsyncDisplayKit/ASImageNode.mm | 10 ++++++++++
 AsyncDisplayKit/ASTextNode.mm  | 10 ++++++++++
 2 files changed, 20 insertions(+)

diff --git a/AsyncDisplayKit/ASImageNode.mm b/AsyncDisplayKit/ASImageNode.mm
index 8609bf489f..024bf1370d 100644
--- a/AsyncDisplayKit/ASImageNode.mm
+++ b/AsyncDisplayKit/ASImageNode.mm
@@ -63,6 +63,16 @@ struct ASImageNodeDrawParameters {
 
 #pragma mark - NSObject
 
++ (void)initialize
+{
+  [super initialize];
+  
+  if (self != [ASImageNode class]) {
+    // Prevent custom drawing in subclasses
+    ASDisplayNodeAssert(!ASSubclassOverridesClassSelector([ASImageNode class], self, @selector(displayWithParameters:isCancelled:)), @"Subclass %@ must not override displayWithParameters:isCancelled: method. Custom drawing in %@ subclass is not supported.", NSStringFromClass(self), NSStringFromClass([ASImageNode class]));
+  }
+}
+
 - (instancetype)init
 {
   if (!(self = [super init]))
diff --git a/AsyncDisplayKit/ASTextNode.mm b/AsyncDisplayKit/ASTextNode.mm
index 9fd9fafb7a..688da55cc7 100644
--- a/AsyncDisplayKit/ASTextNode.mm
+++ b/AsyncDisplayKit/ASTextNode.mm
@@ -71,6 +71,16 @@ struct ASTextNodeDrawParameter {
 
 #pragma mark - NSObject
 
++ (void)initialize
+{
+  [super initialize];
+  
+  if (self != [ASTextNode class]) {
+    // Prevent custom drawing in subclasses
+    ASDisplayNodeAssert(!ASSubclassOverridesClassSelector([ASTextNode class], self, @selector(drawRect:withParameters:isCancelled:isRasterizing:)), @"Subclass %@ must not override drawRect:withParameters:isCancelled:isRasterizing: method. Custom drawing in %@ subclass is not supported.", NSStringFromClass(self), NSStringFromClass([ASTextNode class]));
+  }
+}
+
 static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (instancetype)init