From c9d189293a158d567aaf8f9614c675e990e6d4c0 Mon Sep 17 00:00:00 2001
From: Brandon Shelley <brandon@codeblooded.io>
Date: Tue, 19 Feb 2019 14:15:41 -0800
Subject: [PATCH] Implement shouldTransition(for scrollView: UIScrollView?)
 delegate method

---
 Source/DeckPresentationController.swift           | 4 ++++
 Source/DeckTransitionViewControllerProtocol.swift | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/Source/DeckPresentationController.swift b/Source/DeckPresentationController.swift
index 4d72e2f..f0bc940 100644
--- a/Source/DeckPresentationController.swift
+++ b/Source/DeckPresentationController.swift
@@ -561,6 +561,10 @@ final class DeckPresentationController: UIPresentationController, UIGestureRecog
             return
         }
         
+        if let deckViewController = presentedViewController as? DeckTransitionViewControllerProtocol {
+            guard deckViewController.shouldTransition!(for: ScrollViewDetector(withViewController: presentedViewController).scrollView) else { return }
+        }
+        
         switch gestureRecognizer.state {
         
         case .began:
diff --git a/Source/DeckTransitionViewControllerProtocol.swift b/Source/DeckTransitionViewControllerProtocol.swift
index edd0f9e..dbedb37 100644
--- a/Source/DeckTransitionViewControllerProtocol.swift
+++ b/Source/DeckTransitionViewControllerProtocol.swift
@@ -57,5 +57,11 @@ import UIKit
     ///   `childViewControllerForDeck` variable is also implemented.
     @objc optional var scrollViewForDeck: UIScrollView { get }
     
+    /// Calls a delegate method to determine whether or not a Deck transition
+    /// should take place.
+    
+    /// - Note: Default for this method always returns `true`
+    @objc optional func shouldTransition(for scrollView: UIScrollView?) -> Bool
+    
 }