Fix conflicting pan gestures

Session/Conversations V2/ConversationVC.swift

@@ -7,6 +7,7 @@
 // • Resending failed messages
 // • Link previews
 // • Slight paging glitch
+// • Scrolling bug
 
 final class ConversationVC : BaseVC, ConversationViewModelDelegate, UITableViewDataSource, UITableViewDelegate {
     let thread: TSThread

Session/Conversations V2/Message Cells/VisibleMessageCell.swift

@@ -18,7 +18,13 @@ final class VisibleMessageCell : MessageCell, UITextViewDelegate, BodyTextViewDe
     private lazy var messageStatusImageViewTopConstraint = messageStatusImageView.pin(.top, to: .bottom, of: bubbleView, withInset: 0)
     private lazy var messageStatusImageViewWidthConstraint = messageStatusImageView.set(.width, to: VisibleMessageCell.messageStatusImageViewSize)
     private lazy var messageStatusImageViewHeightConstraint = messageStatusImageView.set(.height, to: VisibleMessageCell.messageStatusImageViewSize)
-    
+
+    private lazy var panGestureRecognizer: UIPanGestureRecognizer = {
+        let result = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
+        result.delegate = self
+        return result
+    }()
+
     private var positionInCluster: Position? {
         guard let viewItem = viewItem else { return nil }
         if viewItem.isFirstInCluster { return .top }
@@ -178,8 +184,6 @@ final class VisibleMessageCell : MessageCell, UITextViewDelegate, BodyTextViewDe
         doubleTapGestureRecognizer.numberOfTapsRequired = 2
         addGestureRecognizer(doubleTapGestureRecognizer)
         tapGestureRecognizer.require(toFail: doubleTapGestureRecognizer)
-        let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
-        panGestureRecognizer.delegate = self
         addGestureRecognizer(panGestureRecognizer)
     }
     
@@ -360,7 +364,7 @@ final class VisibleMessageCell : MessageCell, UITextViewDelegate, BodyTextViewDe
     }
     
     override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
-        if let panGestureRecognizer = gestureRecognizer as? UIPanGestureRecognizer {
+        if gestureRecognizer == panGestureRecognizer {
             let v = panGestureRecognizer.velocity(in: self)
             guard v.x < 0 else { return false }
             return abs(v.x) > abs(v.y)

Session/Conversations V2/Views & Modals/MessagesTableView.swift

@@ -1,7 +1,10 @@
 
 final class MessagesTableView : UITableView {
     var keyboardHeight: CGFloat = 0
-    
+
+    // Overriding contentInset and adjustedContentInset is to keep them from changing when the
+    // conversation view controller is dismissed.
+
     override var contentInset: UIEdgeInsets {
         get { UIEdgeInsets(top: 0, leading: 0, bottom: MessagesTableView.baselineContentInset + keyboardHeight, trailing: 0) }
         set { }
@@ -34,4 +37,13 @@ final class MessagesTableView : UITableView {
         contentInsetAdjustmentBehavior = .never
         keyboardDismissMode = .interactive
     }
+
+    override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        if gestureRecognizer == panGestureRecognizer {
+            let v = panGestureRecognizer.velocity(in: self)
+            return abs(v.x) < 120
+        } else {
+            return true
+        }
+    }
 }