//
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// LxGridViewFlowLayout.m
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// LxGridView
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//
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#import "LxGridViewFlowLayout.h"
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#import "TZTestCell.h"
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#import "UIView+Layout.h"
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#define stringify __STRING
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static CGFloat const PRESS_TO_MOVE_MIN_DURATION = 0.1;
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static CGFloat const MIN_PRESS_TO_BEGIN_EDITING_DURATION = 0.6;
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CG_INLINE CGPoint CGPointOffset(CGPoint point, CGFloat dx, CGFloat dy)
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{
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return CGPointMake(point.x + dx, point.y + dy);
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}
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/*
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此类来源于DeveloperLx的优秀开源项目：LxGridView
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github链接：https://github.com/DeveloperLx/LxGridView
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我对这个类的代码做了一些修改；
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感谢DeveloperLx的优秀代码~
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*/
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@interface LxGridViewFlowLayout () <UIGestureRecognizerDelegate>
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@property (nonatomic,readonly) id<LxGridViewDataSource> dataSource;
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@property (nonatomic,readonly) id<LxGridViewDelegateFlowLayout> delegate;
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@end
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@implementation LxGridViewFlowLayout
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{
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UILongPressGestureRecognizer * _longPressGestureRecognizer;
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UIPanGestureRecognizer * _panGestureRecognizer;
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NSIndexPath * _movingItemIndexPath;
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UIView * _beingMovedPromptView;
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CGPoint _sourceItemCollectionViewCellCenter;
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CADisplayLink * _displayLink;
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CFTimeInterval _remainSecondsToBeginEditing;
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}
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#pragma mark - setup
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- (void)dealloc
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{
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[_displayLink invalidate];
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[self removeGestureRecognizers];
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[self removeObserver:self forKeyPath:@stringify(collectionView)];
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}
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- (instancetype)init
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{
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if (self = [super init]) {
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[self setup];
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}
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return self;
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}
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- (instancetype)initWithCoder:(NSCoder *)coder
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{
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if (self = [super initWithCoder:coder]) {
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[self setup];
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}
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return self;
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}
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- (void)setup
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{
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[self addObserver:self forKeyPath:@stringify(collectionView) options:NSKeyValueObservingOptionNew context:nil];
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}
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- (void)addGestureRecognizers
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{
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self.collectionView.userInteractionEnabled = YES;
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_longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPressGestureRecognizerTriggerd:)];
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_longPressGestureRecognizer.cancelsTouchesInView = NO;
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_longPressGestureRecognizer.minimumPressDuration = PRESS_TO_MOVE_MIN_DURATION;
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_longPressGestureRecognizer.delegate = self;
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for (UIGestureRecognizer * gestureRecognizer in self.collectionView.gestureRecognizers) {
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if ([gestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {
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[gestureRecognizer requireGestureRecognizerToFail:_longPressGestureRecognizer];
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}
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}
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[self.collectionView addGestureRecognizer:_longPressGestureRecognizer];
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_panGestureRecognizer = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panGestureRecognizerTriggerd:)];
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_panGestureRecognizer.delegate = self;
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[self.collectionView addGestureRecognizer:_panGestureRecognizer];
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[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillResignActive:) name:UIApplicationWillResignActiveNotification object:nil];
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}
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- (void)removeGestureRecognizers
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{
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if (_longPressGestureRecognizer) {
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if (_longPressGestureRecognizer.view) {
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[_longPressGestureRecognizer.view removeGestureRecognizer:_longPressGestureRecognizer];
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}
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_longPressGestureRecognizer = nil;
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}
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if (_panGestureRecognizer) {
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if (_panGestureRecognizer.view) {
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[_panGestureRecognizer.view removeGestureRecognizer:_panGestureRecognizer];
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}
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_panGestureRecognizer = nil;
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}
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[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillResignActiveNotification object:nil];
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}
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#pragma mark - getter and setter implementation
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- (id<LxGridViewDataSource>)dataSource
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{
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return (id<LxGridViewDataSource>)self.collectionView.dataSource;
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}
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- (id<LxGridViewDelegateFlowLayout>)delegate
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{
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return (id<LxGridViewDelegateFlowLayout>)self.collectionView.delegate;
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}
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#pragma mark - override UICollectionViewLayout methods
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- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
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{
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NSArray * layoutAttributesForElementsInRect = [super layoutAttributesForElementsInRect:rect];
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for (UICollectionViewLayoutAttributes * layoutAttributes in layoutAttributesForElementsInRect) {
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if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell) {
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layoutAttributes.hidden = [layoutAttributes.indexPath isEqual:_movingItemIndexPath];
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}
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}
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return layoutAttributesForElementsInRect;
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}
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- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
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{
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UICollectionViewLayoutAttributes * layoutAttributes = [super layoutAttributesForItemAtIndexPath:indexPath];
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if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell) {
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layoutAttributes.hidden = [layoutAttributes.indexPath isEqual:_movingItemIndexPath];
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}
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return layoutAttributes;
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}
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#pragma mark - gesture
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- (void)setPanGestureRecognizerEnable:(BOOL)panGestureRecognizerEnable
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{
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_panGestureRecognizer.enabled = panGestureRecognizerEnable;
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}
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- (BOOL)panGestureRecognizerEnable
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{
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return _panGestureRecognizer.enabled;
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}
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- (void)longPressGestureRecognizerTriggerd:(UILongPressGestureRecognizer *)longPress
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{
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switch (longPress.state) {
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case UIGestureRecognizerStatePossible:
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break;
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case UIGestureRecognizerStateBegan:
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{
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if (_displayLink == nil) {
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_displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayLinkTriggered:)];
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_displayLink.frameInterval = 6;
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[_displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
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_remainSecondsToBeginEditing = MIN_PRESS_TO_BEGIN_EDITING_DURATION;
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}
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_movingItemIndexPath = [self.collectionView indexPathForItemAtPoint:[longPress locationInView:self.collectionView]];
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if ([self.dataSource respondsToSelector:@selector(collectionView:canMoveItemAtIndexPath:)] && [self.dataSource collectionView:self.collectionView canMoveItemAtIndexPath:_movingItemIndexPath] == NO) {
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_movingItemIndexPath = nil;
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return;
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}
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if ([self.delegate respondsToSelector:@selector(collectionView:layout:willBeginDraggingItemAtIndexPath:)]) {
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[self.delegate collectionView:self.collectionView layout:self willBeginDraggingItemAtIndexPath:_movingItemIndexPath];
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}
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UICollectionViewCell *sourceCollectionViewCell = [self.collectionView cellForItemAtIndexPath:_movingItemIndexPath];
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TZTestCell *sourceCell = (TZTestCell *)sourceCollectionViewCell;
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_beingMovedPromptView = [[UIView alloc]initWithFrame:CGRectOffset(sourceCollectionViewCell.frame, -10, -10)];
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_beingMovedPromptView.tz_width += 20;
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_beingMovedPromptView.tz_height += 20;
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sourceCollectionViewCell.highlighted = YES;
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UIView * highlightedSnapshotView = [sourceCell snapshotView];
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highlightedSnapshotView.frame = _beingMovedPromptView.bounds;
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highlightedSnapshotView.alpha = 1;
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sourceCollectionViewCell.highlighted = NO;
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UIView * snapshotView = [sourceCell snapshotView];
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snapshotView.frame = _beingMovedPromptView.bounds;
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snapshotView.alpha = 0;
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[_beingMovedPromptView addSubview:snapshotView];
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[_beingMovedPromptView addSubview:highlightedSnapshotView];
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[self.collectionView addSubview:_beingMovedPromptView];
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_sourceItemCollectionViewCellCenter = sourceCollectionViewCell.center;
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typeof(self) __weak weakSelf = self;
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[UIView animateWithDuration:0
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delay:0
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options:UIViewAnimationOptionBeginFromCurrentState
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animations:^{
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typeof(self) __strong strongSelf = weakSelf;
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if (strongSelf) {
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highlightedSnapshotView.alpha = 0;
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snapshotView.alpha = 1;
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}
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}
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completion:^(BOOL finished) {
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typeof(self) __strong strongSelf = weakSelf;
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if (strongSelf) {
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[highlightedSnapshotView removeFromSuperview];
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if ([strongSelf.delegate respondsToSelector:@selector(collectionView:layout:didBeginDraggingItemAtIndexPath:)]) {
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[strongSelf.delegate collectionView:strongSelf.collectionView layout:strongSelf didBeginDraggingItemAtIndexPath:_movingItemIndexPath];
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}
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}
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}];
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[self invalidateLayout];
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}
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break;
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case UIGestureRecognizerStateChanged:
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break;
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case UIGestureRecognizerStateEnded:
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case UIGestureRecognizerStateCancelled:
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{
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[_displayLink invalidate];
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_displayLink = nil;
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NSIndexPath * movingItemIndexPath = _movingItemIndexPath;
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if (movingItemIndexPath) {
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if ([self.delegate respondsToSelector:@selector(collectionView:layout:willEndDraggingItemAtIndexPath:)]) {
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[self.delegate collectionView:self.collectionView layout:self willEndDraggingItemAtIndexPath:movingItemIndexPath];
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}
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_movingItemIndexPath = nil;
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_sourceItemCollectionViewCellCenter = CGPointZero;
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UICollectionViewLayoutAttributes * movingItemCollectionViewLayoutAttributes = [self layoutAttributesForItemAtIndexPath:movingItemIndexPath];
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_longPressGestureRecognizer.enabled = NO;
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typeof(self) __weak weakSelf = self;
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[UIView animateWithDuration:0.2
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delay:0
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options:UIViewAnimationOptionBeginFromCurrentState
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animations:^{
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typeof(self) __strong strongSelf = weakSelf;
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if (strongSelf) {
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_beingMovedPromptView.center = movingItemCollectionViewLayoutAttributes.center;
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}
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}
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completion:^(BOOL finished) {
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_longPressGestureRecognizer.enabled = YES;
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typeof(self) __strong strongSelf = weakSelf;
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if (strongSelf) {
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[_beingMovedPromptView removeFromSuperview];
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_beingMovedPromptView = nil;
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[strongSelf invalidateLayout];
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if ([strongSelf.delegate respondsToSelector:@selector(collectionView:layout:didEndDraggingItemAtIndexPath:)]) {
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[strongSelf.delegate collectionView:strongSelf.collectionView layout:strongSelf didEndDraggingItemAtIndexPath:movingItemIndexPath];
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}
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}
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}];
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}
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}
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break;
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case UIGestureRecognizerStateFailed:
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break;
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default:
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break;
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}
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}
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- (void)panGestureRecognizerTriggerd:(UIPanGestureRecognizer *)pan
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{
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switch (pan.state) {
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case UIGestureRecognizerStatePossible:
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break;
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case UIGestureRecognizerStateBegan:
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case UIGestureRecognizerStateChanged:
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{
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CGPoint panTranslation = [pan translationInView:self.collectionView];
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_beingMovedPromptView.center = CGPointOffset(_sourceItemCollectionViewCellCenter, panTranslation.x, panTranslation.y);
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NSIndexPath * sourceIndexPath = _movingItemIndexPath;
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NSIndexPath * destinationIndexPath = [self.collectionView indexPathForItemAtPoint:_beingMovedPromptView.center];
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if ((destinationIndexPath == nil) || [destinationIndexPath isEqual:sourceIndexPath]) {
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return;
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}
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if ([self.dataSource respondsToSelector:@selector(collectionView:itemAtIndexPath:canMoveToIndexPath:)] && [self.dataSource collectionView:self.collectionView itemAtIndexPath:sourceIndexPath canMoveToIndexPath:destinationIndexPath] == NO) {
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return;
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}
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if ([self.dataSource respondsToSelector:@selector(collectionView:itemAtIndexPath:willMoveToIndexPath:)]) {
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[self.dataSource collectionView:self.collectionView itemAtIndexPath:sourceIndexPath willMoveToIndexPath:destinationIndexPath];
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}
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_movingItemIndexPath = destinationIndexPath;
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typeof(self) __weak weakSelf = self;
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[self.collectionView performBatchUpdates:^{
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typeof(self) __strong strongSelf = weakSelf;
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if (strongSelf) {
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if (sourceIndexPath && destinationIndexPath) {
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[strongSelf.collectionView deleteItemsAtIndexPaths:@[sourceIndexPath]];
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[strongSelf.collectionView insertItemsAtIndexPaths:@[destinationIndexPath]];
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}
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}
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} completion:^(BOOL finished) {
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typeof(self) __strong strongSelf = weakSelf;
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if ([strongSelf.dataSource respondsToSelector:@selector(collectionView:itemAtIndexPath:didMoveToIndexPath:)]) {
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[strongSelf.dataSource collectionView:strongSelf.collectionView itemAtIndexPath:sourceIndexPath didMoveToIndexPath:destinationIndexPath];
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}
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}];
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}
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break;
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case UIGestureRecognizerStateEnded:
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break;
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case UIGestureRecognizerStateCancelled:
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break;
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case UIGestureRecognizerStateFailed:
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break;
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default:
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break;
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}
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}
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- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
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{
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if ([_panGestureRecognizer isEqual:gestureRecognizer]) {
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return _movingItemIndexPath != nil;
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}
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return YES;
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}
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- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
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{
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// only _longPressGestureRecognizer and _panGestureRecognizer can recognize simultaneously
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if ([_longPressGestureRecognizer isEqual:gestureRecognizer]) {
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return [_panGestureRecognizer isEqual:otherGestureRecognizer];
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}
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if ([_panGestureRecognizer isEqual:gestureRecognizer]) {
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return [_longPressGestureRecognizer isEqual:otherGestureRecognizer];
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}
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return NO;
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}
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#pragma mark - displayLink
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- (void)displayLinkTriggered:(CADisplayLink *)displayLink
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{
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if (_remainSecondsToBeginEditing <= 0) {
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[_displayLink invalidate];
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_displayLink = nil;
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}
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_remainSecondsToBeginEditing = _remainSecondsToBeginEditing - 0.1;
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}
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#pragma mark - KVO and notification
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- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
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{
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if ([keyPath isEqualToString:@stringify(collectionView)]) {
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if (self.collectionView) {
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[self addGestureRecognizers];
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}
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else {
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[self removeGestureRecognizers];
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}
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}
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}
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- (void)applicationWillResignActive:(NSNotification *)notificaiton
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{
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_panGestureRecognizer.enabled = NO;
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_panGestureRecognizer.enabled = YES;
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}
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@end
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