support multi section collectionview

Author: grant

Lib/CollectionViewPagingLayout.swift

@@ -43,7 +43,13 @@ public class CollectionViewPagingLayout: UICollectionViewLayout {
     }
 
     private var numberOfItems: Int {
-        collectionView?.numberOfItems(inSection: 0) ?? 0
+        var count = 0;
+        if let sectionCount = collectionView?.numberOfSections {
+            for i in (0 ..< sectionCount) {
+                count += collectionView?.numberOfItems(inSection: i) ?? 0
+            }
+        }
+        return count
     }
 
 
@@ -88,8 +94,23 @@ public class CollectionViewPagingLayout: UICollectionViewLayout {
         let endIndex = min(numberOfItems, initialEndIndex + startIndexOutOfBounds)
 
         var attributesArray: [UICollectionViewLayoutAttributes] = []
+        let sectionCount = collectionView?.numberOfSections ?? 0
         for index in startIndex..<endIndex {
-            let cellAttributes = UICollectionViewLayoutAttributes(forCellWith: IndexPath(row: index, section: 0))
+            var section = 0
+            var row = 0
+            var accIndex = 0
+            for i in (0 ..< sectionCount) {
+                if index - accIndex < collectionView!.numberOfItems(inSection: i) {
+                    section = i
+                    row = index - accIndex
+                    break;
+                }
+                else{
+                    accIndex += collectionView!.numberOfItems(inSection: i)
+                }
+            }
+        
+            let cellAttributes = UICollectionViewLayoutAttributes(forCellWith: IndexPath(row: row, section: section))
             let pageIndex = CGFloat(index)
             let progress = pageIndex - currentScrollOffset
             var zIndex = Int(-abs(round(progress)))