iOS UICollectionView实现卡片效果

 - (void)createCollectionView { CGFloat pading = 0 * SCREEN_WIDTH/375; LHLeftCollocationView * layout = [[LHLeftCollocationView alloc]init]; layout.scrollDirection = UICollectionViewScrollDirectionHorizontal; layout.minimumLineSpacing = pading; layout.minimumInteritemSpacing = pading;// UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];// layout.scrollDirection = UICollectionViewScrollDirectionHorizontal; _collectionView3 = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 100, [UIScreen mainScreen].bounds.size.width, imageHeight * SCREEN_RATE) collectionViewLayout:layout]; _collectionView3.tag = 33; _collectionView3.dataSource = self; _collectionView3.delegate = self; _collectionView3.bounces = NO; _collectionView3.alwaysBounceHorizontal = NO; _collectionView3.alwaysBounceVertical = NO; _collectionView3.backgroundColor = [UIColor grayColor]; _collectionView3.showsHorizontalScrollIndicator = NO; _collectionView3.showsVerticalScrollIndicator = NO; [self.view addSubview:_collectionView3]; [_collectionView3 registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:collectionViewCell];}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ return self.modelArray.count;}- (NSMutableArray *)modelArray { if (!_modelArray) { _modelArray = [NSMutableArray array]; } return _modelArray;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath { CollModel *infoModel = self.modelArray[indexPath.row]; NSLog(@"section:%ld --- row:%ld -----%@",indexPath.section,indexPath.row,infoModel.title); CollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:collectionViewCell forIndexPath:indexPath]; cell.itemModel = infoModel; return cell;}// 返回每个item的大小- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath { CGFloat CWidth = 80 * SCREEN_RATE; CGFloat CHeight = 80 * SCREEN_RATE; return CGSizeMake(CWidth, CHeight);}#pragma mark - UICollectionViewDelegate点击事件- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{ CollModel *infoModel = self.modelArray[indexPath.row]; NSLog(@"infoModelArray----%@",infoModel.title);}

#import "LHLeftCollocationView.h"@implementation LHLeftCollocationView- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity { CGRect targectRect = CGRectMake(proposedContentOffset.x, 0.0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height); NSArray * attriArray = [super layoutAttributesForElementsInRect:targectRect]; CGFloat horizontalCenterX = proposedContentOffset.x + ([UIScreen mainScreen].bounds.size.width); CGFloat offsetAdjustment = CGFLOAT_MAX; for (UICollectionViewLayoutAttributes * layoutAttributes in attriArray) { CGFloat itemHorizontalCenterX = layoutAttributes.center.x; if (fabs(itemHorizontalCenterX-horizontalCenterX) < fabs(offsetAdjustment)) {  offsetAdjustment = itemHorizontalCenterX - horizontalCenterX; } } return CGPointMake(proposedContentOffset.x , proposedContentOffset.y);}CGFloat ActiveDistance = 400; //垂直缩放除以系数CGFloat ScaleFactor = 0.50; //缩放系数 越大缩放越大- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect { NSArray * array = [super layoutAttributesForElementsInRect:rect]; CGRect visibleRect = CGRectZero; visibleRect.origin = self.collectionView.contentOffset; visibleRect.size = self.collectionView.bounds.size; for (UICollectionViewLayoutAttributes *attributes in array) { CGFloat distance = CGRectGetMidX(visibleRect) - attributes.center.x; CGFloat normalizedDistance = fabs(distance / ActiveDistance); CGFloat zoom = 1 - ScaleFactor * normalizedDistance; NSLog(@"zoom----%f",zoom); attributes.transform3D = CATransform3DMakeScale(1.0, zoom, 1.0); //底部显示效果 attributes.frame = CGRectMake(attributes.frame.origin.x, attributes.frame.origin.y + zoom, attributes.size.width, attributes.size.height); //居中显示效果// CGFloat scrollDirectionItemHeight = self.itemSize.height;// CGFloat sideItemFixedOffset = 0;// sideItemFixedOffset = (scrollDirectionItemHeight - scrollDirectionItemHeight * 0.7) / 2;// attributes.center = CGPointMake(attributes.center.x, attributes.center.y + zoom); } return array;}////设置放大动画//-(NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect//{// NSArray *arr = [self getCopyOfAttributes:[super layoutAttributesForElementsInRect:rect]];// //屏幕中线// CGFloat centerX = self.collectionView.contentOffset.x + self.collectionView.bounds.size.width/2.0f;// //刷新cell缩放// for (UICollectionViewLayoutAttributes *attributes in arr) {// CGFloat distance = fabs(attributes.center.x - centerX);// //移动的距离和屏幕宽度的的比例// CGFloat apartScale = distance/self.collectionView.bounds.size.width;// //把卡片移动范围固定到 -π/4到 +π/4这一个范围内// CGFloat scale = fabs(cos(apartScale * M_PI/4));// //设置cell的缩放 按照余弦函数曲线 越居中越趋近于1// attributes.transform = CGAffineTransformMakeScale(1.0, scale);// }// return arr;//}//防止报错 先复制attributes- (NSArray *)getCopyOfAttributes:(NSArray *)attributes{ NSMutableArray *copyArr = [NSMutableArray new]; for (UICollectionViewLayoutAttributes *attribute in attributes) { [copyArr addObject:[attribute copy]]; } return copyArr;}- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds { return true;}@end

#import <Foundation/Foundation.h>@interface CollModel : NSObject@property (nonatomic,strong)NSString *imgUrl;@property (nonatomic,strong)NSString *title;@property (nonatomic,strong)NSString *url;@end 

#import <UIKit/UIKit.h>#import "CollModel.h"@interface CollectionViewCell : UICollectionViewCell@property (nonatomic, strong) CollModel * itemModel;@end#import "CollectionViewCell.h"#define SCREEN_RATE ([UIScreen mainScreen].bounds.size.width/375.0)@interface CollectionViewCell()/** * 存放所有下载操作的队列 */@property (nonatomic, strong) UIImageView *itemIcon;@property (nonatomic, strong) UILabel *itemLabel;@property (nonatomic, strong) UILabel *priceLabel;@end@implementation CollectionViewCell@synthesize itemModel = _itemModel;- (instancetype)initWithFrame:(CGRect)frame{ if (self = [super initWithFrame:frame]) { self.contentView.backgroundColor = [UIColor clearColor]; [self initView]; } return self;}- (void)initView { _itemIcon = [[UIImageView alloc] init]; [self.contentView addSubview:_itemIcon]; _itemIcon.backgroundColor = [UIColor clearColor]; // CGFloat iconWidth = ([UIScreen mainScreen].bounds.size.width / 5.0) * SCREEN_RATE; _itemIcon.frame = CGRectMake(0, 0, self.contentView.frame.size.width, self.contentView.frame.size.height); _itemIcon.center = self.contentView.center;}- (CollModel *)itemModel{ return _itemModel;}- (void)setItemModel:(CollModel *)itemModel{ if (!itemModel) { return; } _itemModel = itemModel; [self setCellWithModel:_itemModel];}- (void)setCellWithModel:(CollModel *)itemModel{ [[NSOperationQueue mainQueue] addOperationWithBlock:^{ _itemIcon.image = [UIImage imageNamed:itemModel.url]; }];}@end