Enable pop transition. Do not need you to add code for this.

Author: seedante

Classes/SDENavigationControllerDelegate.swift

@@ -12,26 +12,29 @@ import UIKit
 class SDENavigationControllerDelegate: NSObject, UINavigationControllerDelegate {
 
     var interactive = false
-    var isPush = false
     var animationController: UIViewControllerAnimatedTransitioning!
     var interactionController: UIPercentDrivenInteractiveTransition?
 
     //MARK: UINavigationControllerDelegate
     func navigationController(navigationController: UINavigationController, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
 
         animationController = SDEPushAndPopAnimationController(operation: operation)
-        isPush = (operation == .Push)
+        if operation == .Push{
+            if let toCollectionVC = toVC as? UICollectionViewController{
+                interactionController =  SDEPopPinchInteractionController(toVC: toCollectionVC, holder: self)
+            }
+        }
+
         return animationController
     }
 
     func navigationController(navigationController: UINavigationController, interactionControllerForAnimationController animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
 
+        // interactive can only update in gesture action
         if interactive{
-            interactionController = UIPercentDrivenInteractiveTransition()
             return interactionController
         }
 
-        interactionController = nil
         return nil
     }
 

Classes/SDEPopPinchInteractionController.swift

@@ -0,0 +1,59 @@
+//
+//  SDEPushAndPopInteractionController.swift
+//  SDECollectionViewAlbumTransition
+//
+//  Created by seedante on 15/10/19.
+//  Copyright © 2015年 seedante. All rights reserved.
+//
+
+import UIKit
+
+class SDEPopPinchInteractionController: UIPercentDrivenInteractiveTransition {
+    var pinchGesture = UIPinchGestureRecognizer()
+    var topVC: UICollectionViewController
+    unowned var holder: SDENavigationControllerDelegate
+
+    init(toVC topVC: UICollectionViewController, holder: SDENavigationControllerDelegate) {
+        self.topVC = topVC
+        self.holder = holder
+        super.init()
+        addPinchGestureOnView(self.topVC.view)
+    }
+
+    func addPinchGestureOnView(view: UIView){
+        pinchGesture.addTarget(self, action: "sde_handlePinch:")
+        view.addGestureRecognizer(pinchGesture)
+    }
+
+    func sde_handlePinch(gesture: UIPinchGestureRecognizer){
+        switch gesture.state{
+        case .Began:
+            if gesture.scale < 1.0{
+                holder.interactive = true
+                topVC.navigationController?.popViewControllerAnimated(true)
+            }
+        case .Changed:
+            if gesture.scale < 1.0{
+                let progress = 1.0 - gesture.scale
+                self.updateInteractiveTransition(progress)
+            }
+        case .Ended:
+            if gesture.scale < 1.0{
+                let progress = 1.0 - gesture.scale
+                if progress > 0.4{
+                    self.finishInteractiveTransition()
+                }else{
+                    self.cancelInteractiveTransition()
+                }
+                holder.interactive = false
+            }
+        default:
+            holder.interactive = false
+        }
+    }
+
+    deinit{
+        print("deinit")
+        pinchGesture.view?.removeGestureRecognizer(pinchGesture)
+    }
+}

SDECollectionViewAlbumTransition.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		FD83B6221BD529C100C4326E /* SDEPopPinchInteractionController.swift in Sources */ = {isa = PBXBuildFile; fileRef = FD83B6211BD529C100C4326E /* SDEPopPinchInteractionController.swift */; settings = {ASSET_TAGS = (); }; };
 		FDB179B41BD00B610029A9AB /* UICollectionViewControllerExtension.swift in Sources */ = {isa = PBXBuildFile; fileRef = FDB179B01BD00B610029A9AB /* UICollectionViewControllerExtension.swift */; settings = {ASSET_TAGS = (); }; };
 		FDBB4B4F1B5BDFBE00B6D674 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = FDBB4B4E1B5BDFBE00B6D674 /* AppDelegate.swift */; };
 		FDBB4B591B5BDFBE00B6D674 /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = FDBB4B571B5BDFBE00B6D674 /* LaunchScreen.storyboard */; };
@@ -24,6 +25,7 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
+		FD83B6211BD529C100C4326E /* SDEPopPinchInteractionController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = SDEPopPinchInteractionController.swift; path = Classes/SDEPopPinchInteractionController.swift; sourceTree = "<group>"; };
 		FDB179B01BD00B610029A9AB /* UICollectionViewControllerExtension.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = UICollectionViewControllerExtension.swift; path = Classes/Extension/UICollectionViewControllerExtension.swift; sourceTree = "<group>"; };
 		FDBB4B4B1B5BDFBE00B6D674 /* SDECollectionViewAlbumTransition.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = SDECollectionViewAlbumTransition.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		FDBB4B4E1B5BDFBE00B6D674 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
@@ -93,6 +95,7 @@
 			isa = PBXGroup;
 			children = (
 				FDBB4B621B5BE02400B6D674 /* SDEPushAndPopAnimationController.swift */,
+				FD83B6211BD529C100C4326E /* SDEPopPinchInteractionController.swift */,
 				FDE437501BCF86FC001A6BF8 /* SDENavigationControllerDelegate.swift */,
 				FDE437551BCFB09B001A6BF8 /* Extension */,
 			);
@@ -187,6 +190,7 @@
 				FDBB4B6C1B5BE02400B6D674 /* SDEAdaptiveAssetCell.swift in Sources */,
 				FDE437511BCF86FC001A6BF8 /* SDENavigationControllerDelegate.swift in Sources */,
 				FDBB4B4F1B5BDFBE00B6D674 /* AppDelegate.swift in Sources */,
+				FD83B6221BD529C100C4326E /* SDEPopPinchInteractionController.swift in Sources */,
 				FDBB4B681B5BE02400B6D674 /* SDEAlbumViewController.swift in Sources */,
 				FDB179B41BD00B610029A9AB /* UICollectionViewControllerExtension.swift in Sources */,
 			);