Disable cache invaldation when the collection view perform an insertion of a new page to the list

Summary: See https://docs.google.com/document/d/1DRB_ZUZU15Cm0968zc7N8WmhUF4aFBhnk-GiR4ssVFQ/edit?tab=t.0

Reviewed By: matrush

Differential Revision: D81792852

fbshipit-source-id: c56f652b22d6adea21629f7c950f174892a59b5e

Author: constantine-fry

Source/IGListKit/IGListCollectionViewLayout.h

@@ -97,6 +97,11 @@ NS_SWIFT_NAME(ListCollectionViewLayout)
 */
 @property (nonatomic, assign) BOOL showHeaderWhenEmpty;
 
+/**
+ Set this to `YES` to keep layout cache when invalidateLayout is called. Default is `NO`.
+*/
+@property (nonatomic, assign) BOOL preserveLayoutCacheOnInvalidateLayout;
+
 /**
  Create and return a new collection view layout.
 

Source/IGListKit/IGListCollectionViewLayout.mm

@@ -204,6 +204,7 @@ - (instancetype)initWithStickyHeaders:(BOOL)stickyHeaders
                                                                                         UICollectionElementKindSectionFooter: [NSMutableDictionary new],
                                                                                         }];
         _minimumInvalidatedSection = NSNotFound;
+        _preserveLayoutCacheOnInvalidateLayout = NO;
     }
     return self;
 }
@@ -390,7 +391,9 @@ - (CGSize)collectionViewContentSize {
 }
 
 - (void)invalidateLayout {
-    _minimumInvalidatedSection = 0;
+    if (!_preserveLayoutCacheOnInvalidateLayout) {
+        _minimumInvalidatedSection = 0;
+    }
     [super invalidateLayout];
 }