Allow to add interface state delegate in background.

Source/ASDisplayNode.mm

@@ -460,6 +460,16 @@ - (void)dealloc
 
 #pragma mark - Loading
 
+#define ASDisplayNodeCallInterfaceStateDelegates(method, __lock) \
+    __lock.lock(); \
+    NSHashTable *delegates = _interfaceStateDelegates; \
+    __lock.unlock(); \
+    for (id <ASInterfaceStateDelegate> delegate in delegates) { \
+      if ([delegate respondsToSelector:@selector(method)]) { \
+        [delegate method]; \
+      } \
+    }
+
 - (BOOL)_locked_shouldLoadViewOrLayer
 {
   ASAssertLocked(__instanceLock__);
@@ -572,12 +582,7 @@ - (void)_didLoad
   for (ASDisplayNodeDidLoadBlock block in onDidLoadBlocks) {
     block(self);
   }
-
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(nodeDidLoad)]) {
-      [delegate nodeDidLoad];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(nodeDidLoad, __instanceLock__);
 }
 
 - (void)didLoad
@@ -1278,15 +1283,12 @@ - (ASLayoutSpec *)layoutSpecThatFits:(ASSizeRange)constrainedSize
 
 - (void)layout
 {
+
   // Hook for subclasses
   ASDisplayNodeAssertMainThread();
   ASAssertUnlocked(__instanceLock__);
   ASDisplayNodeAssertTrue(self.isNodeLoaded);
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(nodeDidLayout)]) {
-      [delegate nodeDidLayout];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(nodeDidLayout, __instanceLock__);
 }
 
 #pragma mark Layout Transition
@@ -1509,12 +1511,7 @@ - (void)_pendingNodeDidDisplay:(ASDisplayNode *)node
   if (_pendingDisplayNodes.isEmpty) {
 
     [self hierarchyDisplayDidFinish];
-
-    for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-      if ([delegate respondsToSelector:@selector(hierarchyDisplayDidFinish)]) {
-        [delegate hierarchyDisplayDidFinish];
-      }
-    }
+    ASDisplayNodeCallInterfaceStateDelegates(hierarchyDisplayDidFinish, __instanceLock__);
 
     BOOL placeholderShouldPersist = [self placeholderShouldPersist];
 
@@ -3017,6 +3014,8 @@ - (void)didExitHierarchy
 
 #pragma mark - Interface State
 
+
+
 /**
  * We currently only set interface state on nodes in table/collection views. For other nodes, if they are
  * in the hierarchy we enable all ASInterfaceState types with `ASInterfaceStateInHierarchy`, otherwise `None`.
@@ -3225,7 +3224,10 @@ - (void)interfaceStateDidChange:(ASInterfaceState)newState fromState:(ASInterfac
   // Subclass hook
   ASAssertUnlocked(__instanceLock__);
   ASDisplayNodeAssertMainThread();
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
+  __instanceLock__.lock();
+  NSHashTable *delegates = _interfaceStateDelegates;
+  __instanceLock__.unlock();
+  for (id <ASInterfaceStateDelegate> delegate in delegates) {
     if ([delegate respondsToSelector:@selector(interfaceStateDidChange:fromState:)]) {
       [delegate interfaceStateDidChange:newState fromState:oldState];
     }
@@ -3241,8 +3243,7 @@ - (BOOL)shouldScheduleDisplayWithNewInterfaceState:(ASInterfaceState)newInterfac
 
 - (void)addInterfaceStateDelegate:(id <ASInterfaceStateDelegate>)interfaceStateDelegate
 {
-  ASDisplayNodeAssertMainThread();
-
+  ASDN::MutexLocker l(__instanceLock__);
   // Not a fan of lazy loading, but this method won't get called very often and avoiding
   // the overhead of creating this is probably worth it.
   if (_interfaceStateDelegates == nil) {
@@ -3253,7 +3254,7 @@ - (void)addInterfaceStateDelegate:(id <ASInterfaceStateDelegate>)interfaceStateD
 
 - (void)removeInterfaceStateDelegate:(id <ASInterfaceStateDelegate>)interfaceStateDelegate
 {
-  ASDisplayNodeAssertMainThread();
+  ASDN::MutexLocker l(__instanceLock__);
   [_interfaceStateDelegates removeObject:interfaceStateDelegate];
 }
 
@@ -3268,11 +3269,7 @@ - (void)didEnterVisibleState
   // subclass override
   ASDisplayNodeAssertMainThread();
   ASAssertUnlocked(__instanceLock__);
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(didEnterVisibleState)]) {
-      [delegate didEnterVisibleState];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(didEnterVisibleState, __instanceLock__);
 #if AS_ENABLE_TIPS
   [ASTipsController.shared nodeDidAppear:self];
 #endif
@@ -3283,11 +3280,7 @@ - (void)didExitVisibleState
   // subclass override
   ASDisplayNodeAssertMainThread();
   ASAssertUnlocked(__instanceLock__);
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(didExitVisibleState)]) {
-      [delegate didExitVisibleState];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(didExitVisibleState, __instanceLock__);
 }
 
 - (BOOL)isInDisplayState
@@ -3301,23 +3294,15 @@ - (void)didEnterDisplayState
   // subclass override
   ASDisplayNodeAssertMainThread();
   ASAssertUnlocked(__instanceLock__);
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(didEnterDisplayState)]) {
-      [delegate didEnterDisplayState];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(didEnterDisplayState, __instanceLock__);
 }
 
 - (void)didExitDisplayState
 {
   // subclass override
   ASDisplayNodeAssertMainThread();
   ASAssertUnlocked(__instanceLock__);
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(didExitDisplayState)]) {
-      [delegate didExitDisplayState];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(didExitDisplayState, __instanceLock__);
 }
 
 - (BOOL)isInPreloadState
@@ -3367,23 +3352,15 @@ - (void)didEnterPreloadState
   if (self.automaticallyManagesSubnodes) {
     [self layoutIfNeeded];
   }
-
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(didEnterPreloadState)]) {
-      [delegate didEnterPreloadState];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(didEnterPreloadState, __instanceLock__);
 }
 
 - (void)didExitPreloadState
 {
   ASDisplayNodeAssertMainThread();
   ASAssertUnlocked(__instanceLock__);
-  for (id <ASInterfaceStateDelegate> delegate in _interfaceStateDelegates) {
-    if ([delegate respondsToSelector:@selector(didExitPreloadState)]) {
-      [delegate didExitPreloadState];
-    }
-  }
+  ASDisplayNodeCallInterfaceStateDelegates(didExitPreloadState, __instanceLock__);
+
 }
 
 - (void)clearContents