Prefer back button over dismiss

In some context this makes more sense, and it will never be confusing.

// FREEBIE

Signal/src/ViewControllers/MediaPageViewController.swift

@@ -104,7 +104,10 @@ class MediaPageViewController: UIPageViewController, UIPageViewControllerDataSou
 
         // Navigation
 
-        self.navigationItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .stop, target: self, action: #selector(didPressDismissButton))
+        // Note: using a custom leftBarButtonItem breaks the interactive pop gesture, but we don't want to be able
+        // to swipe to go back in the pager view anyway, instead swiping back should show the next page.
+        let backButton = OWSViewController.createOWSBackButton(withTarget: self, selector: #selector(didPressDismissButton))
+        self.navigationItem.leftBarButtonItem = backButton
 
         if showAllMediaButton {
             self.navigationItem.rightBarButtonItem = UIBarButtonItem(title: MediaStrings.allMedia, style: .plain, target: self, action: #selector(didPressAllMediaButton))

SignalMessaging/categories/UIViewController+OWS.h

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import <UIKit/UIKit.h>
@@ -19,6 +19,8 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (UIBarButtonItem *)createOWSBackButton;
 
++ (UIBarButtonItem *)createOWSBackButtonWithTarget:(id)target selector:(SEL)selector;
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalMessaging/categories/UIViewController+OWS.m

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "UIView+OWS.h"
@@ -42,6 +42,11 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (UIBarButtonItem *)createOWSBackButtonWithTarget:(id)target selector:(SEL)selector
+{
+    return [[self class] createOWSBackButtonWithTarget:target selector:selector];
+}
+
++ (UIBarButtonItem *)createOWSBackButtonWithTarget:(id)target selector:(SEL)selector
 {
     OWSAssert(target);
     OWSAssert(selector);