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