iOS: tweaked #1137 (full screen)

- Pinch in gesture in a story to force the nav bar to show when hidden for full screen or autoscroll.
- Pinch out gesture to hide it if appropriate.
- Form sheet Safari presentation now only on iPad.
- Responsive swipe is covered by another issue.

clients/ios/Classes/NewsBlurAppDelegate.m

@@ -1779,7 +1779,9 @@
     } else if ([storyBrowser isEqualToString:@"inappsafari"]) {
         self.safariViewController = [[SFSafariViewController alloc] initWithURL:url];
         self.safariViewController.delegate = self;
-        self.safariViewController.modalPresentationStyle = UIModalPresentationPageSheet;
+        if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
+            self.safariViewController.modalPresentationStyle = UIModalPresentationPageSheet;
+        }
         [navigationController presentViewController:self.safariViewController animated:YES completion:nil];
     } else if ([storyBrowser isEqualToString:@"inappsafarireader"]) {
         self.safariViewController = [[SFSafariViewController alloc] initWithURL:url entersReaderIfAvailable:YES];

clients/ios/Classes/StoryDetailViewController.m

@@ -125,6 +125,12 @@
     doubleDoubleTapGesture.delegate = self;
     [self.webView addGestureRecognizer:doubleDoubleTapGesture];
     
+    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
+        UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc]
+                                                  initWithTarget:self action:@selector(pinchGesture:)];
+        [self.webView addGestureRecognizer:pinchGesture];
+    }
+    
     UIScreenEdgePanGestureRecognizer *screenEdgeGesture = [[UIScreenEdgePanGestureRecognizer alloc]
                                                            initWithTarget:self action:@selector(screenEdgeSwipe:)];
     screenEdgeGesture.edges = UIRectEdgeLeft;
@@ -258,6 +264,15 @@
     }
 }
 
+- (void)pinchGesture:(UIPinchGestureRecognizer *)gestureRecognizer {
+    if (gestureRecognizer.state != UIGestureRecognizerStateEnded) {
+        return;
+    }
+    
+    appDelegate.storyPageControl.forceNavigationBarShown = gestureRecognizer.scale < 1;
+    [appDelegate.storyPageControl changedFullscreen];
+}
+
 - (void)screenEdgeSwipe:(UITapGestureRecognizer *)gestureRecognizer {
     NSUserDefaults *userPreferences = [NSUserDefaults standardUserDefaults];
     BOOL swipeEnabled = [[userPreferences stringForKey:@"story_detail_swipe_left_edge"]

clients/ios/Classes/StoryPageControl.h

@@ -86,6 +86,7 @@
 @property (nonatomic, strong) NBNotifier *notifier;
 @property (nonatomic) NSInteger scrollingToPage;
 @property (nonatomic, readonly) BOOL wantNavigationBarHidden;
+@property (nonatomic) BOOL forceNavigationBarShown;
 @property (nonatomic) BOOL currentlyTogglingNavigationBar;
 @property (nonatomic, readonly) BOOL isHorizontal;
 

clients/ios/Classes/StoryPageControl.m

@@ -454,7 +454,7 @@
 - (BOOL)wantNavigationBarHidden {
     NSUserDefaults *preferences = [NSUserDefaults standardUserDefaults];
     
-    return [preferences boolForKey:@"story_full_screen"] || self.autoscrollAvailable;
+    return ([preferences boolForKey:@"story_full_screen"] || self.autoscrollAvailable) && !self.forceNavigationBarShown;
 }
 
 - (void)setNavigationBarHidden:(BOOL)hide {
@@ -1448,8 +1448,7 @@
 }
 
 - (void)changedFullscreen {
-    NSUserDefaults *userPreferences = [NSUserDefaults standardUserDefaults];
-    BOOL wantHidden = [userPreferences boolForKey:@"story_full_screen"];
+    BOOL wantHidden = self.wantNavigationBarHidden;
     BOOL isHidden = self.navigationController.navigationBarHidden;
     
     if (self.currentPage.webView.scrollView.contentOffset.y > 10 || isHidden) {