轮播器(三)--采用UICollectionView实现图片无限轮播

此篇介绍另一种图片轮播器的优化，采用UICollectionView来实现，因为系统已经为UICollectionView做好了优化

#import <UIKit/UIKit.h>@protocol CarouselDelegate <NSObject>//点击事件-(void)clickedAtIndex:(NSInteger)index;@end@interface CarouselView : UIView//代理@property(assign,nonatomic) id<CarouselDelegate> delegate;//数据源@property (strong,nonatomic) NSMutableArray *dataSources;//开启自动滚动-(void)startAutoScroll;@end

#import "CarouselView.h"#import "CarouselCell.h"// 每一组最大的行数#define TotalRowsInSection (2000 * self.dataSources.count)#define DefaultRow (NSUInteger)(TotalRowsInSection * 0.5)@interface CarouselView()<UICollectionViewDataSource,UICollectionViewDelegate>//容器@property (strong, nonatomic) UICollectionView *collectionView;//分页控制器@property (strong, nonatomic) UIPageControl *pageControl;//定时器@property (nonatomic , strong) NSTimer *timer;//自动滚动，默认不开启@property (assign,nonatomic) BOOL autoScroll;@end@implementation CarouselView-(instancetype)initWithFrame:(CGRect)frame{    if (self = [super initWithFrame:frame]) {        self.frame = frame;        [self initSubviews:frame];    }    return self;}-(void)initSubviews:(CGRect)frame{    UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];    flowLayout.itemSize = frame.size;    flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;    flowLayout.minimumLineSpacing = 0;        self.collectionView = [[UICollectionView alloc] initWithFrame:self.bounds collectionViewLayout:flowLayout];    self.collectionView.delegate = self;    self.collectionView.dataSource = self;    self.collectionView.showsHorizontalScrollIndicator = NO;    self.collectionView.pagingEnabled = YES;    self.collectionView.backgroundColor = [UIColor lightGrayColor];    [self addSubview:self.collectionView];        [self.collectionView registerClass:[CarouselCell class] forCellWithReuseIdentifier:@"carouselCell"];        self.pageControl = [[UIPageControl alloc] init];    self.pageControl.center = CGPointMake(frame.size.width * 0.5, frame.size.height - 30);    self.pageControl.bounds = CGRectMake(0, 0, 150, 40);    self.pageControl.pageIndicatorTintColor = [UIColor grayColor];    self.pageControl.currentPageIndicatorTintColor = [UIColor whiteColor];    self.pageControl.enabled = NO;    self.pageControl.numberOfPages = self.dataSources.count;        [self addSubview:self.pageControl];    if (self.autoScroll) {        [self addTimer];    }}-(void)setDataSources:(NSMutableArray *)dataSources{    _dataSources = dataSources;        //设置分页控制器页数    self.pageControl.numberOfPages = self.dataSources.count;        //刷新数据    [self.collectionView reloadData];        //设置默认组    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:DefaultRow inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];}-(void)startAutoScroll{    self.autoScroll = YES;    [self addTimer];}/** *  移除定时器 */- (void)removeTimer{    [self.timer invalidate];    self.timer = nil;}/** *  添加定时器 */- (void)addTimer{    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(next) userInfo:nil repeats:YES];    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];}/** *  下一页 */- (void)next{    NSIndexPath *visiablePath = [[self.collectionView indexPathsForVisibleItems] firstObject];        NSUInteger visiableItem = visiablePath.item;    if ((visiablePath.item % self.dataSources.count)  == 0) { // 第0张图片        [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:DefaultRow inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];        visiableItem = DefaultRow ;    }        NSUInteger nextItem = visiableItem + 1;    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:nextItem inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];    }#pragma mark - UICollectionViewDataSource- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return TotalRowsInSection;}-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{    return 1;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    static NSString *ID = @"carouselCell";        CarouselCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:ID forIndexPath:indexPath];    if (!cell) {        cell = [[NSBundle mainBundle] loadNibNamed:@"CarouselCell" owner:self options:nil][0];    }    cell.dataModel = self.dataSources[indexPath.item % self.dataSources.count];    return cell;}#pragma mark - UICollectionViewDelegate/** *  cell显示结束之后调用(滑动了一页) */- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath{    NSIndexPath *visiablePath = [[collectionView indexPathsForVisibleItems] firstObject];    //设置pageControl的当前页    self.pageControl.currentPage = visiablePath.item % self.dataSources.count;}-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    NSInteger index = indexPath.item % self.dataSources.count;    if ([self.delegate respondsToSelector:@selector(clickedAtIndex:)]) {        [self.delegate clickedAtIndex:index];    }}#pragma mark - UIScrollViewDelegate- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{    if (self.autoScroll) {        [self removeTimer];    }}- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{    if (self.autoScroll) {        [self addTimer];    }}@end

#import <UIKit/UIKit.h>#import "CarouselModel.h"@interface CarouselCell : UICollectionViewCell//数据模型@property (strong,nonatomic) CarouselModel *dataModel;@end

#import "CarouselCell.h"#import "UIImageView+WebCache.h"@interface CarouselCell()//显示的图片@property (weak,nonatomic) IBOutlet UIImageView *imageView;//标题@property (weak, nonatomic) IBOutlet UILabel *titleLabel;@end@implementation CarouselCell-(instancetype)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        self = [[NSBundle mainBundle]loadNibNamed:@"CarouselCell" owner:self options:nil].lastObject;    }    return self;}//重写属性，设置值-(void)setDataModel:(CarouselModel *)dataModel{    _dataModel = dataModel;    [self.imageView sd_setImageWithURL:[[NSURL alloc] initWithString:_dataModel.imageUrl] placeholderImage:[UIImage imageNamed:@"1"]];    self.titleLabel.text = _dataModel.labelText;}- (void)awakeFromNib {    [super awakeFromNib];    // Initialization code}@end

VC中使用

self.automaticallyAdjustsScrollViewInsets = NO;        NSMutableArray *dataList = [[NSMutableArray alloc]init];    NSMutableArray *dataArr = [[NSMutableArray alloc]initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"carouselArr.plist" ofType:nil]];    for (NSDictionary *dic in dataArr) {        CarouselModel *model = [[CarouselModel alloc]init];        model.imageUrl = [dic objectForKey:@"imageUrl"];        model.contentUrl = [dic objectForKey:@"contentUrl"];        model.labelText = [dic objectForKey:@"textLable"];        [dataList addObject:model];    }        CarouselView *view1 = [[CarouselView alloc]initWithFrame:CGRectMake(20, 100, self.view.frame.size.width - 40, (self.view.frame.size.width - 40) * 0.5)];    view1.delegate = self;    [view1 startAutoScroll];    view1.dataSources = dataList;    [self.view addSubview:view1];