Merge branch 'development' of https://github.com/hyouuu/MessageKit into development

Sources/Controllers/MessagesViewController+Keyboard.swift

@@ -45,9 +45,15 @@ internal extension MessagesViewController {
 
     @objc
     private func handleTextViewDidBeginEditing(_ notification: Notification) {
-        if scrollsToBottomOnKeyboardBeginsEditing {
-            guard let inputTextView = notification.object as? InputTextView, inputTextView === messageInputBar.inputTextView else { return }
-            messagesCollectionView.scrollToBottom(animated: true)
+        if scrollsToLastItemOnKeyboardBeginsEditing || scrollsToBottomOnKeyboardBeginsEditing {
+            guard let inputTextView = notification.object as? InputTextView,
+                inputTextView === messageInputBar.inputTextView else { return }
+
+            if scrollsToLastItemOnKeyboardBeginsEditing {
+                messagesCollectionView.scrollToLastItem()
+            } else {
+                messagesCollectionView.scrollToBottom(animated: true)
+            }
         }
     }
 

Sources/Controllers/MessagesViewController.swift

@@ -36,10 +36,18 @@ UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {
     /// The `InputBarAccessoryView` used as the `inputAccessoryView` in the view controller.
     open lazy var messageInputBar = InputBarAccessoryView()
 
+    /// A Boolean value that determines whether the `MessagesCollectionView` scrolls to the
+    /// last item whenever the `InputTextView` begins editing.
+    ///
+    /// The default value of this property is `false`.
+    /// NOTE: This calls scrollToLastItem where as the below flag calls scrollToBottome - check methods for differences
+    open var scrollsToLastItemOnKeyboardBeginsEditing: Bool = false
+
     /// A Boolean value that determines whether the `MessagesCollectionView` scrolls to the
     /// bottom whenever the `InputTextView` begins editing.
     ///
     /// The default value of this property is `false`.
+    /// NOTE: This calls scrollToBottome where as the above flag calls  scrollToLastItem - check methods for differences
     open var scrollsToBottomOnKeyboardBeginsEditing: Bool = false
     
     /// A Boolean value that determines whether the `MessagesCollectionView`

Sources/Views/MessagesCollectionView.swift

@@ -100,8 +100,24 @@ open class MessagesCollectionView: UICollectionView {
         cell?.handleTapGesture(gesture)
     }
 
+    // NOTE: It's possible for small content size this wouldn't work - https://github.com/MessageKit/MessageKit/issues/725
+    public func scrollToLastItem(at pos: UICollectionView.ScrollPosition = .bottom, animated: Bool = true) {
+        guard numberOfSections > 0 else { return }
+        
+        let lastSection = numberOfSections - 1
+        let lastItem = numberOfItems(inSection: lastSection) - 1
+        
+        guard lastItem >= 0 else { return }
+        
+        let indexPath = IndexPath(row: lastItem, section: lastSection)
+        scrollToItem(at: indexPath, at: pos, animated: animated)
+    }
+    
+    // NOTE: This method seems to cause crash in certain cases - https://github.com/MessageKit/MessageKit/issues/725
+    // Could try using `scrollToLastItem` above
     public func scrollToBottom(animated: Bool = false) {
-        performBatchUpdates(nil) { _ in
+        performBatchUpdates(nil) { [weak self] _ in
+            guard let self = self else { return }
             let collectionViewContentHeight = self.collectionViewLayout.collectionViewContentSize.height
             self.scrollRectToVisible(CGRect(0.0, collectionViewContentHeight - 1.0, 1.0, 1.0), animated: animated)
         }