iOS之轮播图(collectionView)加定时器

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今天为大家分享一波轮播图,本人不才,希望此分享对大家有用。今天为什么写这个呢,之前写过项目用scrollView封装写过轮播图,但是感觉不是很好,而且传值也很不好写,所以今天用collectionView写的轮播图,传值也很是好写的。

5517BA7A-0DE8-43B6-8C97-7BACA687416D.png

<1>先定一些我们需要的属性


@property (nonatomic, retain) UICollectionView *collection;
@property (nonatomic, retain) NSMutableArray *marr;// 存图片的数组
@property (nonatomic, retain) UIPageControl *page;
@property (nonatomic, retain) NSTimer *timer;
// 调用的一些方法
- (void)viewDidLoad {
    [super viewDidLoad];
    [self createCollectionView];
    [self createPhone];
    [self createPage];
    [self addTimer];
    // Do any additional setup after loading the view, typically from a nib.
}

<2>//先做一些事前工作,把collectionView铺好


    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];
    layout.itemSize = CGSizeMake(WIDTH, 300);
    layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    layout.minimumLineSpacing = 0;
    self.collection = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, WIDTH, 300) collectionViewLayout:layout];
    [self.view addSubview:self.collection];
    self.collection.backgroundColor = [UIColor whiteColor];
    self.collection.pagingEnabled = YES;//开启翻页效果
    self.collection.delegate = self;
    self.collection.dataSource = self;
    self.collection.showsHorizontalScrollIndicator = NO;//滑条不出现
    [self.collection registerClass:[CellOfFirst class] forCellWithReuseIdentifier:@"pool"];
    

<3>collectionView 的协议方法


- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
   
    return self.marr.count;// 返回图片的个数
}
// 说一下为什么返回100个分区
// 我们可以将第50个分区的一组图片作为用户看到的第一组图片,这样就实现轮播的效果了。(100分区足够了,除非脑残划100次)
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 100;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
// 自定义的Cell类
    CellOfFirst *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"pool" forIndexPath:indexPath];
   cell.pic.image = self.marr[indexPath.row];
    return cell;
    
}

// 本地的图片

- (void)createPhone {
    self.marr = [NSMutableArray array];
    for (int i = 1; i < 12; i++) {
        NSString *name = [NSString stringWithFormat:@"123_%d.jpg",i];
        UIImage *image = [UIImage imageNamed:name];
        [self.marr addObject:image];
    }
    //设置起始位置
    [self.collection scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:50] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
}

// 获取pageControoler

// 别忘记调用呦
- (void)createPage {
    self.page = [[UIPageControl alloc]initWithFrame:CGRectMake(0, 250, WIDTH, 50)];
    [self.view addSubview:self.page];
    self.page.numberOfPages = self.marr.count;
 }

// 当图片划得时候已经减速时

// collectionView继承于scrollview 所以我们可用此方法
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    // 计算page算法
    int page = (int) (scrollView.contentOffset.x / WIDTH + 0.5) % self.marr.count;
    self.page.currentPage = page;
    
    
}

// 我们可以添加定时器了 (一样别忘记获取完图片调用)

- (void)addTimer {
    self.timer = [NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];
    [[NSRunLoop mainRunLoop] addTimer:_timer forMode:NSRunLoopCommonModes];
}
- (void)nextImage {
    //设置当前 indePath
    NSIndexPath *currrentIndexPath = [[self.collection indexPathsForVisibleItems]lastObject];
    NSIndexPath *currentIndexPathReset = [NSIndexPath indexPathForItem:currrentIndexPath.item inSection:50];
    [self.collection scrollToItemAtIndexPath:currentIndexPathReset atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
    // 设置下一个滚动的item
    NSInteger nextItem = currentIndexPathReset.item +1;
    NSInteger nextSection = currentIndexPathReset.section;
    if (nextItem==self.marr.count) {
        // 当item等于轮播图的总个数的时候
        // item等于0, 分区加1
        // 未达到的时候永远在50分区中
        nextItem=0;
        nextSection++;
    }
    NSIndexPath *nextIndexPath = [NSIndexPath indexPathForItem:nextItem inSection:nextSection];
      [self.collection scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
}

// 当用户自己划图片时 当然我们也需要定时器被移除 (时机很重要)

- (void)removeTimer{
    [self.timer invalidate];
    self.timer = nil;
  }

// 当图片即将开始被拖拽时 我们将定时器移除

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    
    [self removeTimer];
}

// 当图片已经完成被拖拽时 我们还需加上定时器

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    
    [self addTimer];
}

这些做完我们基本就完成轮播图自动轮播了,大家有兴趣的可以尝试下。

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