Fabric: Proper handling of memory pressure event in RCTComponentViewR…

…egistry

Summary: View recycling can be pretty aggressive and memory intensive, so we can properly react on system memory-pressure notification.

Reviewed By: mdvacca

Differential Revision: D13176278

fbshipit-source-id: 38ea1b27da988aeaaa5db6ac0b94389a0bd2799e

React/Fabric/Mounting/RCTComponentViewRegistry.mm

@@ -81,11 +81,22 @@ - (instancetype)init
     _recyclePool = [NSMapTable mapTableWithKeyOptions:NSPointerFunctionsOpaquePersonality | NSPointerFunctionsOpaqueMemory
                                          valueOptions:NSPointerFunctionsObjectPersonality];
     _componentViewFactory = [RCTComponentViewFactory standardComponentViewFactory];
+
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(handleApplicationDidReceiveMemoryWarningNotification)
+                                                 name:UIApplicationDidReceiveMemoryWarningNotification
+                                               object:nil];
   }
 
   return self;
 }
 
+- (void)dealloc
+{
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
 - (UIView<RCTComponentViewProtocol> *)dequeueComponentViewWithComponentHandle:(ComponentHandle)componentHandle
                                                                           tag:(ReactTag)tag
 {
@@ -177,4 +188,9 @@ - (void)_enqueueComponentViewWithComponentHandle:(ComponentHandle)componentHandl
   [componentViews addObject:componentView];
 }
 
+- (void)handleApplicationDidReceiveMemoryWarningNotification
+{
+  [_recyclePool removeAllObjects];
+}
+
 @end