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Direction to Scroll #33

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Direction to Scroll #33

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b7ff5b2
new: dev: add direction top/bottom
Apr 6, 2016
54d9b96
new: dev: add ability to finish infinity scrolling without animation
Apr 6, 2016
788c830
flag for note checking if content height is more than view height
emilwojtaszek Nov 23, 2016
c2381a1
add getter and setter
emilwojtaszek Nov 23, 2016
0b36017
fix compile issue
emilwojtaszek Nov 24, 2016
301b291
remove extra inset for top scrolling
Jan 23, 2017
d8b580e
rename remove infinite scoll method name
May 9, 2017
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23 changes: 19 additions & 4 deletions Classes/UIScrollView+InfiniteScroll.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,18 @@

NS_ASSUME_NONNULL_BEGIN

typedef NS_ENUM(NSInteger, UIScrollViewInfiniteScrollDirection) {
UIScrollViewInfiniteScrollDirectionTop = 0,
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@pronebird pronebird Apr 15, 2016 •
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Upward direction is default in this PR. Would be great to maintain the existing behavior which is downward "refresh". This is better achieved by moving infinite scroll direction to state object and then resetting it to bottom during -init.

UIScrollViewInfiniteScrollDirectionBottom = 1
};

@interface UIScrollView (InfiniteScroll)

/**
* Indicates whether inifinte scrol should be on top or bottom
*/
@property (nonatomic, assign) UIScrollViewInfiniteScrollDirection infiniteScrollDirection;

/**
* Flag that indicates whether infinite scroll is animating
*/
Expand All @@ -36,7 +46,7 @@ NS_ASSUME_NONNULL_BEGIN
/**
* Infinite indicator view
*
* You can set your own custom view instead of default activity indicator,
* You can set your own custom view instead of default activity indicator,
* make sure it implements methods below:
*
* * `- (void)startAnimating`
Expand All @@ -51,6 +61,11 @@ NS_ASSUME_NONNULL_BEGIN
*/
@property (nonatomic) CGFloat infiniteScrollIndicatorMargin;

/**
* A flag that indicates whether validate if content is higher that view height. Default NO.
*/
@property (nonatomic) BOOL allowTriggerOnUnfilledContent;

/**
* Setup infinite scroll handler
*
Expand All @@ -61,7 +76,7 @@ NS_ASSUME_NONNULL_BEGIN
/**
* Unregister infinite scroll
*/
- (void)removeInfiniteScroll;
- (void)removeInfiniteScroll_;

/**
* Finish infinite scroll animations
Expand All @@ -71,15 +86,15 @@ NS_ASSUME_NONNULL_BEGIN
*
* @param handler a completion block handler called when animation finished
*/
- (void)finishInfiniteScrollWithCompletion:(nullable void(^)(__pb_kindof(UIScrollView *) scrollView))handler;
- (void)finishInfiniteScroll:(BOOL)animated completion:(nullable void(^)(__pb_kindof(UIScrollView *) scrollView))handler;

/**
* Finish infinite scroll animations
*
* You must call this method from your infinite scroll handler to finish all
* animations properly and reset infinite scroll state
*/
- (void)finishInfiniteScroll;
- (void)finishInfiniteScroll:(BOOL)animated;
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@pronebird pronebird Apr 15, 2016 •
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Would be better to add DEPRECATED attribute and keep the method around for a while so others could adjust.


@end

Expand Down
164 changes: 126 additions & 38 deletions Classes/UIScrollView+InfiniteScroll.m
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Expand Up @@ -34,6 +34,7 @@ static void PBSwizzleMethod(Class c, SEL original, SEL alternate) {

// Keys for values in associated dictionary
static const void *kPBInfiniteScrollStateKey = &kPBInfiniteScrollStateKey;
static const void *kPBInfiniteScrollDirectionKey = &kPBInfiniteScrollDirectionKey;
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Any reason why it cannot reside within pb_infiniteScrollState?


/**
* Infinite scroll state class.
Expand Down Expand Up @@ -67,6 +68,12 @@ @interface _PBInfiniteScrollState : NSObject
*/
@property CGFloat extraBottomInset;

/**
* Extra padding to push indicator view below view bounds.
* Used in case when content size is smaller than view bounds
*/
@property CGFloat extraTopInset;

/**
* Indicator view inset.
* Essentially is equal to indicator view height.
Expand All @@ -78,6 +85,11 @@ @interface _PBInfiniteScrollState : NSObject
*/
@property CGFloat indicatorMargin;

/**
* A flag that indicates whether validate if content is higher that view height. Default NO.
*/
@property (nonatomic) BOOL allowTriggerOnUnfilledContent;

/**
* Infinite scroll handler block
*/
Expand Down Expand Up @@ -120,6 +132,15 @@ @implementation UIScrollView (InfiniteScroll)

#pragma mark - Public methods

- (void)setInfiniteScrollDirection:(UIScrollViewInfiniteScrollDirection)infiniteScrollDirection {
objc_setAssociatedObject(self, kPBInfiniteScrollDirectionKey, @(infiniteScrollDirection), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (UIScrollViewInfiniteScrollDirection)infiniteScrollDirection {
NSNumber *direction = objc_getAssociatedObject(self, kPBInfiniteScrollDirectionKey);
return direction.integerValue;
}

- (BOOL)isAnimatingInfiniteScroll {
return self.pb_infiniteScrollState.loading;
}
Expand All @@ -143,7 +164,7 @@ - (void)addInfiniteScrollWithHandler:(void(^)(__pb_kindof(UIScrollView *) scroll
state.initialized = YES;
}

- (void)removeInfiniteScroll {
- (void)removeInfiniteScroll_ {
_PBInfiniteScrollState *state = self.pb_infiniteScrollState;

// Ignore multiple calls to remove infinite scroll
Expand All @@ -162,13 +183,13 @@ - (void)removeInfiniteScroll {
self.pb_infiniteScrollState.initialized = NO;
}

- (void)finishInfiniteScroll {
[self finishInfiniteScrollWithCompletion:nil];
- (void)finishInfiniteScroll:(BOOL)animated {
[self finishInfiniteScroll:animated completion:nil];
}

- (void)finishInfiniteScrollWithCompletion:(nullable void(^)(__pb_kindof(UIScrollView *) scrollView))handler {
- (void)finishInfiniteScroll:(BOOL)animated completion:(nullable void(^)(__pb_kindof(UIScrollView *) scrollView))handler {
if(self.pb_infiniteScrollState.loading) {
[self pb_stopAnimatingInfiniteScrollWithCompletion:handler];
[self pb_stopAnimatingInfiniteScroll:animated completion:handler];
}
}

Expand All @@ -189,7 +210,7 @@ - (UIActivityIndicatorViewStyle)infiniteScrollIndicatorStyle {
- (void)setInfiniteScrollIndicatorView:(UIView *)indicatorView {
// make sure indicator is initially hidden
indicatorView.hidden = YES;

self.pb_infiniteScrollState.indicatorView = indicatorView;
}

Expand All @@ -205,11 +226,19 @@ - (CGFloat)infiniteScrollIndicatorMargin {
return self.pb_infiniteScrollState.indicatorMargin;
}

- (void)setAllowTriggerOnUnfilledContent:(BOOL)allowTriggerOnUnfilledContent {
self.pb_infiniteScrollState.allowTriggerOnUnfilledContent = allowTriggerOnUnfilledContent;
}

- (BOOL)allowTriggerOnUnfilledContent {
return self.pb_infiniteScrollState.allowTriggerOnUnfilledContent;
}

#pragma mark - Private dynamic properties

- (_PBInfiniteScrollState *)pb_infiniteScrollState {
_PBInfiniteScrollState *state = objc_getAssociatedObject(self, kPBInfiniteScrollStateKey);

if(!state) {
state = [[_PBInfiniteScrollState alloc] init];

Expand Down Expand Up @@ -275,12 +304,27 @@ - (void)pb_setContentSize:(CGSize)contentSize {
* @return CGFloat
*/
- (CGFloat)pb_clampContentSizeToFitVisibleBounds:(CGSize)contentSize {

CGFloat inset = self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionTop ? [self pb_originalTopInset] + self.contentInset.bottom : [self pb_originalBottomInset] + self.contentInset.top;
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@pronebird pronebird Apr 15, 2016 •
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Long ternary operations especially when doing math can be misleading or confusing. if-else or switch-case would be better.



// Find minimum content height. Only original insets are used in calculation.
CGFloat minHeight = self.bounds.size.height - self.contentInset.top - [self pb_originalBottomInset];

CGFloat minHeight = self.bounds.size.height - inset;
return MAX(contentSize.height, minHeight);
}

/**
* Returns top inset without extra padding and indicator padding.
*
* @return CGFloat
*/
- (CGFloat)pb_originalTopInset {
_PBInfiniteScrollState *state = self.pb_infiniteScrollState;

return self.contentInset.top - state.extraTopInset - state.indicatorInset;
}

/**
* Returns bottom inset without extra padding and indicator padding.
*
Expand Down Expand Up @@ -345,9 +389,11 @@ - (CGFloat)pb_infiniteIndicatorRowHeight {
*/
- (void)pb_positionInfiniteScrollIndicatorWithContentSize:(CGSize)contentSize {
UIView *activityIndicator = [self pb_getOrCreateActivityIndicatorView];
CGFloat contentHeight = [self pb_clampContentSizeToFitVisibleBounds:contentSize];
CGFloat contentHeight = self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionTop ? 0.0f : [self pb_clampContentSizeToFitVisibleBounds:contentSize];
CGFloat indicatorRowHeight = [self pb_infiniteIndicatorRowHeight];
CGPoint center = CGPointMake(contentSize.width * 0.5, contentHeight + indicatorRowHeight * 0.5);
CGFloat sign = self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionTop ? -1 : 1;

CGPoint center = CGPointMake(contentSize.width * 0.5, sign * (contentHeight + indicatorRowHeight * 0.5));

if(!CGPointEqualToPoint(activityIndicator.center, center)) {
activityIndicator.center = center;
Expand Down Expand Up @@ -375,23 +421,41 @@ - (void)pb_startAnimatingInfiniteScroll {

UIEdgeInsets contentInset = self.contentInset;

// Make a room to accommodate indicator view
contentInset.bottom += indicatorInset;

// We have to pad scroll view when content height is smaller than view bounds.
// This will guarantee that indicator view appears at the very bottom of scroll view.
CGFloat adjustedContentHeight = [self pb_clampContentSizeToFitVisibleBounds:self.contentSize];
CGFloat extraBottomInset = adjustedContentHeight - self.contentSize.height;
CGFloat extraInset = adjustedContentHeight - self.contentSize.height;

// Make a room to accommodate indicator view
if (self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionTop) {

//
contentInset.top += indicatorInset;

// Add empty space padding
contentInset.top += 0.0f;

//
state.extraTopInset = 0.0f;
}

// Add empty space padding
contentInset.bottom += extraBottomInset;
// bottom
else {

//
contentInset.bottom += indicatorInset;

// Add empty space padding
contentInset.bottom += extraInset;

//
state.extraBottomInset = extraInset;
}

// Save indicator view inset
state.indicatorInset = indicatorInset;

// Save extra inset
state.extraBottomInset = extraBottomInset;

// Update infinite scroll state
state.loading = YES;

Expand All @@ -401,7 +465,7 @@ - (void)pb_startAnimatingInfiniteScroll {
[self pb_scrollToInfiniteIndicatorIfNeeded];
}
}];

TRACE(@"Start animating.");
}

Expand All @@ -410,25 +474,38 @@ - (void)pb_startAnimatingInfiniteScroll {
*
* @param handler a completion handler
*/
- (void)pb_stopAnimatingInfiniteScrollWithCompletion:(nullable void(^)(id scrollView))handler {
- (void)pb_stopAnimatingInfiniteScroll:(BOOL)animated completion:(nullable void(^)(id scrollView))handler {
_PBInfiniteScrollState *state = self.pb_infiniteScrollState;
UIView *activityIndicator = self.infiniteScrollIndicatorView;
UIEdgeInsets contentInset = self.contentInset;

// Remove row height inset
contentInset.bottom -= state.indicatorInset;
// top
if (self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionTop) {

contentInset.top -= state.indicatorInset;

// Remove extra inset added to pad infinite scroll
contentInset.top -= state.extraTopInset;
}

// Remove extra inset added to pad infinite scroll
contentInset.bottom -= state.extraBottomInset;
// bottom
else {
// Remove row height inset
contentInset.bottom -= state.indicatorInset;

// Remove extra inset added to pad infinite scroll
contentInset.bottom -= state.extraBottomInset;
}

// Reset indicator view inset
state.indicatorInset = 0;

// Reset extra bottom inset
state.extraBottomInset = 0;
state.extraTopInset = 0;

// Animate content insets
[self pb_setScrollViewContentInset:contentInset animated:YES completion:^(BOOL finished) {
[self pb_setScrollViewContentInset:contentInset animated:animated completion:^(BOOL finished) {
// Curtain is closing they're throwing roses at my feet
if([activityIndicator respondsToSelector:@selector(stopAnimating)]) {
[activityIndicator performSelector:@selector(stopAnimating)];
Expand Down Expand Up @@ -461,18 +538,22 @@ - (void)pb_stopAnimatingInfiniteScrollWithCompletion:(nullable void(^)(id scroll
- (void)pb_scrollViewDidScroll:(CGPoint)contentOffset {
_PBInfiniteScrollState *state = self.pb_infiniteScrollState;

CGFloat contentHeight = [self pb_clampContentSizeToFitVisibleBounds:self.contentSize];

// The lower bound when infinite scroll should kick in
CGFloat actionOffset = contentHeight - self.bounds.size.height + [self pb_originalBottomInset];

// Disable infinite scroll when scroll view is empty
// Default UITableView reports height = 1 on empty tables
BOOL hasActualContent = (self.contentSize.height > 1);
CGFloat actionOffset = 0;

// is there any content?
if(!hasActualContent) {
return;
if (self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionBottom) {
CGFloat contentHeight = [self pb_clampContentSizeToFitVisibleBounds:self.contentSize];

// The lower bound when infinite scroll should kick in
actionOffset = contentHeight - self.bounds.size.height + [self pb_originalBottomInset];

// Disable infinite scroll when scroll view is empty
// Default UITableView reports height = 1 on empty tables
BOOL hasActualContent = (self.contentSize.height > 1);

// is there any content?
if(!hasActualContent) {
return;
}
}

// is user initiated?
Expand All @@ -485,7 +566,10 @@ - (void)pb_scrollViewDidScroll:(CGPoint)contentOffset {
return;
}

if(contentOffset.y > actionOffset) {
BOOL validContentHeight = !self.allowTriggerOnUnfilledContent ? self.contentSize.height > CGRectGetHeight(self.frame) : YES;
BOOL animate = self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionBottom ? contentOffset.y > actionOffset : contentOffset.y < 0 && validContentHeight;

if(animate) {
TRACE(@"Action.");

[self pb_startAnimatingInfiniteScroll];
Expand All @@ -499,6 +583,10 @@ - (void)pb_scrollViewDidScroll:(CGPoint)contentOffset {
* Scrolls down to activity indicator position if activity indicator is partially visible
*/
- (void)pb_scrollToInfiniteIndicatorIfNeeded {

// top
if (self.infiniteScrollDirection == UIScrollViewInfiniteScrollDirectionTop) return;
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Indicator can be half visible, this is when we need to scroll up or down to reveal or hide it based on scroll position. It's similar to how search bar works in table views.


// do not interfere with user
if([self isDragging]) {
return;
Expand Down