From 9052794fdfd817859be02b00f2b0c5144abd660f Mon Sep 17 00:00:00 2001
From: DreamingInBinary <jordan@dreaminginbinary.co>
Date: Fri, 12 Jan 2018 14:29:09 -0600
Subject: [PATCH 1/4] Hook into scrollview for percent complete

---
 .../BFRImageViewController.m                   | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/BFRImageViewController/BFRImageViewController.m b/BFRImageViewController/BFRImageViewController.m
index c28d9c9..1c74001 100644
--- a/BFRImageViewController/BFRImageViewController.m
+++ b/BFRImageViewController/BFRImageViewController.m
@@ -12,7 +12,7 @@
 #import "BFRImageTransitionAnimator.h"
 #import "BFRImageViewerConstants.h"
 
-@interface BFRImageViewController () <UIPageViewControllerDataSource>
+@interface BFRImageViewController () <UIPageViewControllerDataSource, UIScrollViewDelegate>
 
 /*! This view controller just acts as a container to hold a page view controller, which pages between the view controllers that hold an image. */
 @property (strong, nonatomic, nonnull) UIPageViewController *pagerVC;
@@ -106,6 +106,14 @@ - (void)viewDidLoad {
     [[self view] addSubview:[self.pagerVC view]];
     [self.pagerVC didMoveToParentViewController:self];
     
+    // Attach to pager controller's scrollview for parallax effect when swiping between images
+    for (UIView *subview in self.pagerVC.view.subviews) {
+        if ([subview isKindOfClass:[UIScrollView class]]) {
+            ((UIScrollView *)subview).delegate = self;
+            break;
+        }
+    }
+    
     // Add chrome to UI now if we aren't waiting to be peeked into
     if (!self.isBeingUsedFor3DTouch) {
         [self addChromeToUI];
@@ -200,6 +208,14 @@ - (UIViewController *)pageViewController:(UIPageViewController *)pageViewControl
     return vc;
 }
 
+#pragma mark - Scrollview Delegate
+
+- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
+    CGPoint point = scrollView.contentOffset;
+    CGFloat percentComplete = fabs(point.x - self.view.frame.size.width)/self.view.frame.size.width;
+    NSLog(@"Percent scrolled %f", percentComplete);
+}
+
 #pragma mark - Utility methods
 - (void)dismiss {
     // If we dismiss from a different image than what was animated in - don't do the custom dismiss transition animation

From fb01df26d48f27c2a57e959c845b867fb3b6c003 Mon Sep 17 00:00:00 2001
From: DreamingInBinary <jordan@dreaminginbinary.co>
Date: Tue, 16 Jan 2018 09:41:35 -0600
Subject: [PATCH 2/4] Parallax view, correct coding style for pragma marks

---
 BFRImageViewController/BFRBackLoadedImageSource.m    |  2 ++
 .../BFRImageContainerViewController.m                |  9 ++++++++-
 BFRImageViewController/BFRImageTransitionAnimator.m  |  4 ++++
 BFRImageViewController/BFRImageViewController.m      | 12 ++++++++++++
 4 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/BFRImageViewController/BFRBackLoadedImageSource.m b/BFRImageViewController/BFRBackLoadedImageSource.m
index 7b1ce39..164f778 100644
--- a/BFRImageViewController/BFRBackLoadedImageSource.m
+++ b/BFRImageViewController/BFRBackLoadedImageSource.m
@@ -25,6 +25,7 @@ @interface BFRBackLoadedImageSource()
 @implementation BFRBackLoadedImageSource
 
 #pragma mark - Initializers
+
 - (instancetype)initWithInitialImage:(UIImage *)image hiResURL:(NSURL *)url {
     self = [super init];
     
@@ -39,6 +40,7 @@ - (instancetype)initWithInitialImage:(UIImage *)image hiResURL:(NSURL *)url {
 }
 
 #pragma mark - Backloading
+
 - (void)loadHighFidelityImage {
     [[PINRemoteImageManager sharedImageManager] downloadImageWithURL:self.url options:PINRemoteImageManagerDisallowAlternateRepresentations progressDownload:nil completion:^(PINRemoteImageManagerResult * _Nonnull result) {
         dispatch_async(dispatch_get_main_queue(), ^{
diff --git a/BFRImageViewController/BFRImageContainerViewController.m b/BFRImageViewController/BFRImageContainerViewController.m
index a775ac2..afd017b 100644
--- a/BFRImageViewController/BFRImageContainerViewController.m
+++ b/BFRImageViewController/BFRImageContainerViewController.m
@@ -42,6 +42,7 @@ @interface BFRImageContainerViewController () <UIScrollViewDelegate, UIGestureRe
 @implementation BFRImageContainerViewController
 
 #pragma mark - Lifecycle
+
 // With peeking and popping, setting up your subviews in loadView will throw an exception
 - (void)viewDidLoad {
     [super viewDidLoad];
@@ -117,6 +118,7 @@ - (void)dealloc {
 }
 
 #pragma mark - UI Methods
+
 - (UIScrollView *)createScrollView {
     UIScrollView *sv = [[UIScrollView alloc] initWithFrame:self.view.bounds];
     sv.delegate = self;
@@ -204,6 +206,7 @@ - (void)addImageToScrollView {
 }
 
 #pragma mark - Backloaded Image Notification
+
 - (void)handleHiResImageDownloaded:(NSNotification *)note {
     UIImage *hiResImg = note.object;
     
@@ -214,6 +217,7 @@ - (void)handleHiResImageDownloaded:(NSNotification *)note {
 }
 
 #pragma mark - Gesture Recognizer Delegate
+
 // If we have more than one image, this will cancel out dragging horizontally to make it easy to navigate between images
 - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
     CGPoint velocity = [(UIPanGestureRecognizer *)gestureRecognizer velocityInView:self.scrollView];
@@ -221,6 +225,7 @@ - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
 }
 
 #pragma mark - Scrollview Delegate
+
 - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
     return self.scrollView.subviews.firstObject;
 }
@@ -231,6 +236,7 @@ - (void)scrollViewDidZoom:(UIScrollView *)scrollView {
 }
 
 #pragma mark - Scrollview Util Methods
+
 /*! This calculates the correct zoom scale for the scrollview once we have the image's size */
 - (void)setMaxMinZoomScalesForCurrentBounds {
     // Sizes
@@ -342,7 +348,6 @@ - (void)handleDrag:(UIPanGestureRecognizer *)recognizer {
 }
 
 - (void)showActivitySheet:(UILongPressGestureRecognizer *)longPress {
-    
     UIActivityViewController *activityVC;
     if (longPress.state == UIGestureRecognizerStateBegan) {
         if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
@@ -362,6 +367,7 @@ - (void)showActivitySheet:(UILongPressGestureRecognizer *)longPress {
 }
 
 #pragma mark - Image Asset Retrieval
+
 - (void)retrieveImageFromAsset {
     if (![self.imgSrc isKindOfClass:[PHAsset class]]) {
         return;
@@ -418,6 +424,7 @@ - (void)retrieveImageFromURL {
 }
 
 #pragma mark - Misc. Methods
+
 - (void)dismissUI {
     [[NSNotificationCenter defaultCenter] postNotificationName:NOTE_VC_SHOULD_DISMISS object:nil];
 }
diff --git a/BFRImageViewController/BFRImageTransitionAnimator.m b/BFRImageViewController/BFRImageTransitionAnimator.m
index c50a63f..9bae2a4 100644
--- a/BFRImageViewController/BFRImageTransitionAnimator.m
+++ b/BFRImageViewController/BFRImageTransitionAnimator.m
@@ -25,6 +25,7 @@ @interface BFRImageTransitionAnimator()
 @implementation BFRImageTransitionAnimator
 
 #pragma mark - Initialization
+
 - (instancetype)init {
     self = [super init];
     
@@ -50,6 +51,7 @@ - (void)handleCancelCustomTransitionNotification:(NSNotification *)notification
 }
 
 #pragma mark - Utils
+
 - (UIImageView *)temporaryImageView {
     if (self.animatedImage == nil) return nil;
     
@@ -86,6 +88,7 @@ - (CGRect)imageFinalFrameDestinationForImageView:(UIImageView *)imageView inView
 }
 
 #pragma mark - Animator delegate
+
 - (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
     return self.animationDuration;
 }
@@ -170,6 +173,7 @@ - (void)performDismissingAnimation:(id<UIViewControllerContextTransitioning>)tra
 }
 
 #pragma mark - Transitioning Delegate
+
 - (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source {
     return self;
 }
diff --git a/BFRImageViewController/BFRImageViewController.m b/BFRImageViewController/BFRImageViewController.m
index 1c74001..8a1bc1c 100644
--- a/BFRImageViewController/BFRImageViewController.m
+++ b/BFRImageViewController/BFRImageViewController.m
@@ -35,11 +35,15 @@ @interface BFRImageViewController () <UIPageViewControllerDataSource, UIScrollVi
 /*! This is used for nothing more than to defer the hiding of the status bar until the view appears to avoid any awkward jumps in the presenting view. */
 @property (nonatomic, getter=shouldHideStatusBar) BOOL hideStatusBar;
 
+/*! This creates the parallax scrolling effect by essentially clipping the scrolled images and moving with the touch point in scrollViewDidScroll. */
+@property (strong, nonatomic, nonnull) UIView *parallaxView;
+
 @end
 
 @implementation BFRImageViewController
 
 #pragma mark - Initializers
+
 - (instancetype)initWithImageSource:(NSArray *)images {
     self = [super init];
     
@@ -49,6 +53,7 @@ - (instancetype)initWithImageSource:(NSArray *)images {
         self.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
         self.enableDoneButton = YES;
         self.showDoneButtonOnLeft = YES;
+        self.parallaxView = [UIView new];
     }
     
     return self;
@@ -64,12 +69,14 @@ - (instancetype)initForPeekWithImageSource:(NSArray *)images {
         self.enableDoneButton = YES;
         self.showDoneButtonOnLeft = YES;
         self.usedFor3DTouch = YES;
+        self.parallaxView = [UIView new];
     }
     
     return self;
 }
 
 #pragma mark - View Lifecycle
+
 - (void)viewDidLoad {
     [super viewDidLoad];
     
@@ -137,6 +144,7 @@ - (void)viewWillLayoutSubviews {
 }
 
 #pragma mark - Status bar
+
 - (BOOL)prefersStatusBarHidden{
     return self.shouldHideStatusBar;
 }
@@ -146,6 +154,7 @@ - (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
 }
 
 #pragma mark - Chrome
+
 - (void)addChromeToUI {
     if (self.enableDoneButton) {
         NSBundle *bundle = [NSBundle bundleForClass:[self class]];
@@ -178,6 +187,7 @@ - (void)updateChromeFrames {
 }
 
 #pragma mark - Pager Datasource
+
 - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
     NSUInteger index = ((BFRImageContainerViewController *)viewController).pageIndex;
     
@@ -217,6 +227,7 @@ - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
 }
 
 #pragma mark - Utility methods
+
 - (void)dismiss {
     // If we dismiss from a different image than what was animated in - don't do the custom dismiss transition animation
     if (self.startingIndex != ((BFRImageContainerViewController *)self.pagerVC.viewControllers.firstObject).pageIndex) {
@@ -257,6 +268,7 @@ - (BOOL)prefersHomeIndicatorAutoHidden {
 }
 
 #pragma mark - Memory Considerations
+
 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     NSLog(@"BFRImageViewer: Dismissing due to memory warning.");

From 923f051be969778144d834091fbbedbfcaa9758f Mon Sep 17 00:00:00 2001
From: DreamingInBinary <jordan@dreaminginbinary.co>
Date: Tue, 16 Jan 2018 10:02:58 -0600
Subject: [PATCH 3/4] First go parallax effect

---
 .../BFRImageViewController.m                  | 40 +++++++++++++++++--
 .../BFRImageViewerConstants.h                 |  3 ++
 .../BFRImageViewerConstants.m                 |  2 +
 3 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/BFRImageViewController/BFRImageViewController.m b/BFRImageViewController/BFRImageViewController.m
index 8a1bc1c..d5f99d1 100644
--- a/BFRImageViewController/BFRImageViewController.m
+++ b/BFRImageViewController/BFRImageViewController.m
@@ -117,6 +117,13 @@ - (void)viewDidLoad {
     for (UIView *subview in self.pagerVC.view.subviews) {
         if ([subview isKindOfClass:[UIScrollView class]]) {
             ((UIScrollView *)subview).delegate = self;
+            self.parallaxView.backgroundColor = self.view.backgroundColor;
+            [subview addSubview:self.parallaxView];
+            
+            CGRect parallaxSeparatorFrame = CGRectZero;
+            parallaxSeparatorFrame.size = [self sizeForParallaxView];
+            self.parallaxView.frame = parallaxSeparatorFrame;
+            
             break;
         }
     }
@@ -173,6 +180,7 @@ - (void)addChromeToUI {
     }
 }
 
+//TODO: Update parallax effect view
 - (void)updateChromeFrames {
     if (self.enableDoneButton) {
         CGFloat buttonX = self.showDoneButtonOnLeft ? 20 : CGRectGetMaxX(self.view.bounds) - 37;
@@ -218,12 +226,36 @@ - (UIViewController *)pageViewController:(UIPageViewController *)pageViewControl
     return vc;
 }
 
-#pragma mark - Scrollview Delegate
+#pragma mark - Scrollview Delegate + Parallax Effect
 
 - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
-    CGPoint point = scrollView.contentOffset;
-    CGFloat percentComplete = fabs(point.x - self.view.frame.size.width)/self.view.frame.size.width;
-    NSLog(@"Percent scrolled %f", percentComplete);
+    [self updateParallaxViewFrame:scrollView];
+}
+
+- (void)updateParallaxViewFrame:(UIScrollView *)scrollView {
+    CGRect bounds = scrollView.bounds;
+    CGRect parallaxSeparatorFrame = self.parallaxView.frame;
+
+    CGPoint offset = bounds.origin;
+    CGFloat pageWidth = bounds.size.width;
+
+    NSInteger firstPageIndex = floorf(CGRectGetMinX(bounds) / pageWidth);
+
+    CGFloat x = offset.x - pageWidth * firstPageIndex;
+    CGFloat percentage = x / pageWidth;
+
+    parallaxSeparatorFrame.origin.x = pageWidth * (firstPageIndex + 1) - parallaxSeparatorFrame.size.width * percentage;
+
+    self.parallaxView.frame = parallaxSeparatorFrame;
+}
+
+- (CGSize)sizeForParallaxView {
+    CGSize parallaxSeparatorSize = CGSizeZero;
+    
+    parallaxSeparatorSize.width = PARALLAX_EFFECT_WIDTH * 2;
+    parallaxSeparatorSize.height = self.view.bounds.size.height;
+    
+    return parallaxSeparatorSize;
 }
 
 #pragma mark - Utility methods
diff --git a/BFRImageViewController/BFRImageViewerConstants.h b/BFRImageViewController/BFRImageViewerConstants.h
index 23bf764..aa92d20 100644
--- a/BFRImageViewController/BFRImageViewerConstants.h
+++ b/BFRImageViewController/BFRImageViewerConstants.h
@@ -25,4 +25,7 @@ extern NSString * const GENERAL_OK;
 extern NSString * const HI_RES_IMG_ERROR_DOMAIN;
 extern NSInteger const HI_RES_IMG_ERROR_CODE;
 
+// Misc
+extern NSInteger const PARALLAX_EFFECT_WIDTH;
+
 @end
diff --git a/BFRImageViewController/BFRImageViewerConstants.m b/BFRImageViewController/BFRImageViewerConstants.m
index be86b4e..5191512 100644
--- a/BFRImageViewController/BFRImageViewerConstants.m
+++ b/BFRImageViewController/BFRImageViewerConstants.m
@@ -23,4 +23,6 @@ @implementation BFRImageViewerConstants
 NSString * const HI_RES_IMG_ERROR_DOMAIN = @"com.bfrImageViewer.backLoadedImgSource";
 NSInteger const HI_RES_IMG_ERROR_CODE = 44;
 
+NSInteger const PARALLAX_EFFECT_WIDTH = 20;
+
 @end

From 7a7b990187f7980f11c719f43cc437fb4c47995b Mon Sep 17 00:00:00 2001
From: DreamingInBinary <jordan@dreaminginbinary.co>
Date: Tue, 16 Jan 2018 10:30:21 -0600
Subject: [PATCH 4/4] Fix hidden state of parallax view

---
 BFRImageViewController/BFRImageViewController.m        | 10 ++++++++--
 .../BFRImageViewer/ThirdViewController.m               |  6 +++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/BFRImageViewController/BFRImageViewController.m b/BFRImageViewController/BFRImageViewController.m
index d5f99d1..756c09b 100644
--- a/BFRImageViewController/BFRImageViewController.m
+++ b/BFRImageViewController/BFRImageViewController.m
@@ -118,6 +118,7 @@ - (void)viewDidLoad {
         if ([subview isKindOfClass:[UIScrollView class]]) {
             ((UIScrollView *)subview).delegate = self;
             self.parallaxView.backgroundColor = self.view.backgroundColor;
+            self.parallaxView.hidden = YES;
             [subview addSubview:self.parallaxView];
             
             CGRect parallaxSeparatorFrame = CGRectZero;
@@ -145,7 +146,7 @@ - (void)viewWillAppear:(BOOL)animated {
     }];
 }
 
-- (void)viewWillLayoutSubviews {
+- (void)viewDidLayoutSubviews {
     [super viewWillLayoutSubviews];
     [self updateChromeFrames];
 }
@@ -180,7 +181,6 @@ - (void)addChromeToUI {
     }
 }
 
-//TODO: Update parallax effect view
 - (void)updateChromeFrames {
     if (self.enableDoneButton) {
         CGFloat buttonX = self.showDoneButtonOnLeft ? 20 : CGRectGetMaxX(self.view.bounds) - 37;
@@ -192,6 +192,8 @@ - (void)updateChromeFrames {
         
         self.doneButton.frame = CGRectMake(buttonX, closeButtonY, 17, 17);
     }
+    
+    self.parallaxView.hidden = YES;
 }
 
 #pragma mark - Pager Datasource
@@ -228,6 +230,10 @@ - (UIViewController *)pageViewController:(UIPageViewController *)pageViewControl
 
 #pragma mark - Scrollview Delegate + Parallax Effect
 
+- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
+    self.parallaxView.hidden = NO;
+}
+
 - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
     [self updateParallaxViewFrame:scrollView];
 }
diff --git a/BFRImageViewerDemo/BFRImageViewer/ThirdViewController.m b/BFRImageViewerDemo/BFRImageViewer/ThirdViewController.m
index 73be809..05f81d6 100644
--- a/BFRImageViewerDemo/BFRImageViewer/ThirdViewController.m
+++ b/BFRImageViewerDemo/BFRImageViewer/ThirdViewController.m
@@ -32,8 +32,8 @@ - (void)viewDidLoad {
 
     // To use the custom transition animation with BFRImageViewer
     // 1) Have an instance of BFRImageTransitionAnimator around
-    // 2) Set it's aniamtedImage, animatedImageContainer and imageOriginFrame. Optionally, set the desiredContentMode
-    // 3) When you present the BFRImageViewController, set it's transitioningDelegate to your BFRImageTransitionAnimator instance.
+    // 2) Set its animatedImage, animatedImageContainer and imageOriginFrame. Optionally, set the desiredContentMode
+    // 3) When you present the BFRImageViewController, set its transitioningDelegate to your BFRImageTransitionAnimator instance.
     // You can see all of this in action in openImageViewerWithTransition below
     
     // Object to create all the animations
@@ -68,7 +68,7 @@ - (void)openImageViewerWithTransition {
     self.imageViewAnimator.animatedImageContainer = self.imageView;
     // The image that will be animated
     self.imageViewAnimator.animatedImage = self.imageView.image;
-    // The rect the image will aniamte to and from
+    // The rect the image will animate to and from
     self.imageViewAnimator.imageOriginFrame = self.imageView.frame;
     // Optional - but you'll want this to match the view's content mode that the image is housed in
     self.imageViewAnimator.desiredContentMode = self.imageView.contentMode;