Added a way to get the current index on paging

Example/MSPeekCollectionViewDelegateImplementation/ViewController.swift

@@ -92,4 +92,8 @@ extension ViewController: UICollectionViewDelegate {
     func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
         behavior.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
     }
+
+    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
+        print(behavior.currentIndex)
+    }
 }

Example/Podfile.lock

@@ -1,5 +1,5 @@
 PODS:
-  - MSPeekCollectionViewDelegateImplementation (3.1.0)
+  - MSPeekCollectionViewDelegateImplementation (3.1.1)
 
 DEPENDENCIES:
   - MSPeekCollectionViewDelegateImplementation (from `../`)
@@ -9,7 +9,7 @@ EXTERNAL SOURCES:
     :path: "../"
 
 SPEC CHECKSUMS:
-  MSPeekCollectionViewDelegateImplementation: 7115b89c6065613e77045836730eb2f63c3bc958
+  MSPeekCollectionViewDelegateImplementation: f86fd6a6ce284723343e8697a013f5294c05e745
 
 PODFILE CHECKSUM: 8d230cee08c8a8b7e62859eff8016277efe2311d
 

MSPeekCollectionViewDelegateImplementation.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'MSPeekCollectionViewDelegateImplementation'
-  s.version          = '3.1.0'
+  s.version          = '3.1.1'
   s.summary          = 'A custom paging behavior that peeks the previous and next items in a collection view'
   s.swift_version    = '5.0'
 

README.md

@@ -182,6 +182,10 @@ extension ViewController: UICollectionViewDelegate {
     func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
         behavior.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
     }
+
+    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
+        print(behavior.currentIndex)
+    }
 }
 ```
 
@@ -197,6 +201,14 @@ You can do something like:
 behavior.scrollToItem(at: 1, animated: true)
 ```
 
+### Listen to index changes
+You can use the scroll view's delegate function to do that (Make sure you conform to `UICollectionViewDelegate`):
+```
+func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
+    print(behavior.currentIndex)
+}
+```
+
 ## Customization
 ### Vertical Scroll Direction
 The implementation supports collection views with vertical directions and will automatically position cells correctly, you can set the scrolling and peeking to be vertical using:

Sources/MSPeekCollectionViewDelegateImplementation/MSCollectionViewPaging.swift

@@ -36,6 +36,10 @@ public class MSCollectionViewPaging: NSObject {
 
     var currentContentOffset: CGFloat = 0
 
+    public var currentIndex: Int {
+        return dataSource?.collectionViewPaging(self, indexForItemAtOffset: currentContentOffset) ?? 0
+    }
+
     var velocityThreshold: CGFloat {
         return dataSource?.collectionViewPagingVelocityThreshold(self) ?? 0
     }

Sources/MSPeekCollectionViewDelegateImplementation/MSCollectionViewPeekingBehavior.swift

@@ -53,6 +53,11 @@ public class MSCollectionViewPeekingBehavior {
         return layout.collectionView?.numberOfItems(inSection: 0) ?? 0
     }
 
+    /// Returns the current index of the left most item
+    public var currentIndex: Int {
+        return paging.currentIndex
+    }
+
     public init(cellSpacing: CGFloat = 20, cellPeekWidth: CGFloat = 20, minimumItemsToScroll: Int? = nil, maximumItemsToScroll: Int? = nil, numberOfItemsToShow: Int = 1, scrollDirection: UICollectionView.ScrollDirection = .horizontal, velocityThreshold: CGFloat = 0.2) {
         self.cellSpacing = cellSpacing
         self.cellPeekWidth = cellPeekWidth