Add delegate to check if pan gesture should begin

PanModal/Controller/PanModalPresentationController.swift

@@ -816,6 +816,14 @@ private extension PanModalPresentationController {
 
 extension PanModalPresentationController: UIGestureRecognizerDelegate {
 
+    /**
+     Asks the delegate if the pan modal should begin to track the pan gesture
+     */
+    public func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        guard gestureRecognizer == panGestureRecognizer else { return true }
+        return presentable?.shouldBeginPanGesture(panGestureRecognizer) ?? true
+    }
+
     /**
      Do not require any other gesture recognizers to fail
      */

PanModal/Presentable/PanModalPresentable+Defaults.swift

@@ -96,6 +96,10 @@ public extension PanModalPresentable where Self: UIViewController {
     var showDragIndicator: Bool {
         return shouldRoundTopCorners
     }
+
+    func shouldBeginPanGesture(_ panModalGestureRecognizer: UIPanGestureRecognizer) -> Bool {
+        return true
+    }
 
     func shouldRespond(to panModalGestureRecognizer: UIPanGestureRecognizer) -> Bool {
         return true

PanModal/Presentable/PanModalPresentable.swift

@@ -173,6 +173,15 @@ public protocol PanModalPresentable: AnyObject {
      */
     var showDragIndicator: Bool { get }
 
+    /**
+     Asks the delegate if the pan modal should begin to track the pan gesture.
+
+     Return false to not track the pan gesture and possibly let other observers track the gesture
+
+     Default value is true.
+     */
+    func shouldBeginPanGesture(_ panModalGestureRecognizer: UIPanGestureRecognizer) -> Bool
+
     /**
      Asks the delegate if the pan modal should respond to the pan modal gesture recognizer.