一句代码搞定无限图片轮播器,抽取API

项目介绍：

最近闲来无事,封装了一个无限图片轮播器,基于collectionView完成,抽取了两个API,一个是创建轮播器,一个是点击图片的跳转,使用的话,直接把JZLCycleView这个文件夹拖进项目,调用API就完成了,非常简单。

1.无限轮播思路:
建了图片数量*3个数的cell,然后去一直显示中间的cell,到最后一组的第一个,无动画滚动到中间一组的第一个,到第一组的最后一个,无动画滚动到中间一组的最后一个

2.调用的方法,使用直接调用API

_cycleView = [JZLCycleView cycleCollectionViewWithFrame:CGRectMake(0, 0, JZLScreenWidth, JZLCycleViewHeight) PlaceholderImage:[UIImage imageNamed:@"placeholderImage"]];
//小圆点颜色设置,自己根据需求更改,默认黑色和白色
    _cycleView.pageControl.pageIndicatorTintColor = [UIColor orangeColor];
    _cycleView.pageControl.currentPageIndicatorTintColor = [UIColor whiteColor];
//如果要跳转记得遵守协议,设置代理
    _cycleView.delegate = self;
    _cycleView.clickItemBlock = ^(NSInteger index){
        NSLog(@"%ld",(long)index);
    };
    [self.view addSubview:_cycleView];

2.1跳转这一块封装了两个,一个block,一个代理,个人认为代理更清晰一些

//block跳转
    _cycleView.clickItemBlock = ^(NSInteger index){
        NSLog(@"%ld",(long)index);
    };

//代理跳转
- (void)selectItemAtIndex:(NSInteger)index {
    NSLog(@"%ld",index);
}

3.实现
1.初始化轮播器,这里抽取了两个,一个是加载本地图片,一个是加载网路url,一般开发中第二个用的比较多

/**
 加载后台获取的url图片

 @param frame 图片轮播器的frame
 @param placeholderImage 占位图
 @return 图片轮播图
 */
+ (instancetype)cycleCollectionViewWithFrame: (CGRect)frame PlaceholderImage: (UIImage *)placeholderImage;

/**
 加载本地图片

 @param frame 图片轮播器frame
 @param imageArray 本地图片数组(数组里元素为imageView)
 @param placeholderImage 占位图
 @return 图片轮播器
 */
+ (instancetype)cycleCollectionViewWithFrame: (CGRect)frame imageArray: (NSArray *)imageArray PlaceholderImage: (UIImage *)placeholderImage;

2.主要的就是去完成collectionView

//设置collectionView
- (void)setupCollcetionView {
    //collcetionView
    UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
    UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:self.bounds collectionViewLayout:flowLayout];
    flowLayout.itemSize = CGSizeMake(self.bounds.size.width, self.bounds.size.height);
    flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    flowLayout.minimumLineSpacing = 0;
    collectionView.pagingEnabled = YES;
    collectionView.bounces = NO;
    collectionView.showsHorizontalScrollIndicator = NO;
    collectionView.delegate = self;
    collectionView.dataSource = self;
    [collectionView registerClass:[JZLCollectionViewCell class] forCellWithReuseIdentifier: reuseID];
    [self addSubview:collectionView];
    self.collectionView = collectionView;
    //pageControl
    self.pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(self.bounds.size.width / 2 - 50, self.bounds.size.height - 20, 100, 20)];
    //默认一张,加载图片后自动更新
    self.pageControl.numberOfPages = 1;
    self.pageControl.currentPage = 0;
    [self addSubview:self.pageControl];

}

3.添加定时器以及手动滚动和自动滚动的切换

//设置页码
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    self.pageControl.currentPage = (NSInteger)(scrollView.contentOffset.x / scrollView.bounds.size.width)%self.imageArray.count;
}

//添加定时器
- (void)addTimer {
    self.timer = [NSTimer scheduledTimerWithTimeInterval:automaticTime target:self selector:@selector(automaticScrollCollectionCell) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}

//删除定时器
- (void)deleteTimer {
    [self.timer invalidate];
    self.timer = nil;
}
//自动滚动
- (void)automaticScrollCollectionCell {
    self.index++;
    if (self.imageArray.count == 0) {
        return;
    }else {
        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:self.index inSection:0];
        [self.collectionView scrollToItemAtIndexPath:indexPath atScrollPosition:0 animated:YES];

        if (indexPath.row == self.imageArray.count * 2) {
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
                NSIndexPath *indexPath = [NSIndexPath indexPathForItem:self.imageArray.count inSection:0];
                [self.collectionView scrollToItemAtIndexPath:indexPath atScrollPosition:0 animated:NO];
            });

        }

        self.pageControl.currentPage = self.index % self.imageArray.count ;
    }

}
//手动滚动时删除定时器
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    [self deleteTimer];
    if (self.imageArray.count == 0) {
        return;
    }else {
        if (self.index == self.imageArray.count - 1) {
            [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:self.imageArray.count * 2 - 1 inSection:0] atScrollPosition:0 animated:NO];
        }

        if (self.index == self.imageArray.count * 2) {
            [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:self.imageArray.count inSection:0] atScrollPosition:0 animated:NO];
        }
    }



}
//停止滚动时打开定时器
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    [self addTimer];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    self.index = (NSInteger)(scrollView.contentOffset.x / scrollView.bounds.size.width);

}

git地址:https://github.com/allenjzl/JZLCycleView.git