UICollectionView实现无限轮播

矫情吗；* 2022-03-22 10:50 280阅读 0赞

# [UICollectionView实现无限轮播][UICollectionView] #

\#import "KGNewsController.h"  
\#import "KGNewsCell.h"  
\#import "KGNews.h"  
\#import "MJExtension.h"  
  
// 生成一个字符串  
\#define NSString(...) \[NSString stringWithFormat:\_\_VA\_ARGS\_\_\]

\#define KGCount 100

@interface KGNewsController ()<UICollectionViewDataSource, UICollectionViewDelegate>  
@property (strong, nonatomic) IBOutlet UICollectionView \*collectionView;  
/\*\* 模型数组 \*/  
@property (strong, nonatomic) NSArray \*dataSourceArr;  
@property (strong, nonatomic) UIPageControl \*pageControl;  
@property (strong, nonatomic) NSTimer \*timer;  
@end  
  
@implementation KGNewsController  
\- (NSArray \*)dataSourceArr \{  
    if (!\_dataSourceArr) \{  
        // 模型数组  
        \_dataSourceArr = \[KGNews objectArrayWithFilename:@"newses.plist"\];  
    \}  
    return \_dataSourceArr;  
\}  
  
static NSString \*cell\_id = @"KGNewsCell";  
  
\- (void)viewDidLoad \{  
    \[super viewDidLoad\];  
     
    // 注册nib里面的cell  
    \[self.collectionView registerNib:\[UINib nibWithNibName:@"KGNewsCell" bundle:\[NSBundle mainBundle\]\] forCellWithReuseIdentifier:cell\_id\];  
     
    // 在100组中间开始展示图片  
    \[self.collectionView scrollToItemAtIndexPath:\[NSIndexPath indexPathForItem:0 inSection:KGCount / 2\] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES\];  
     
    // 添加定时器  
    \[self addTimer\];  
     
    // 添加pageControll  
    UIPageControl \*pageControl = \[\[UIPageControl alloc\] init\];  
    pageControl.center = CGPointMake(self.view.bounds.size.width / 2, 200);  
    pageControl.pageIndicatorTintColor = \[UIColor redColor\];  
    pageControl.currentPageIndicatorTintColor = \[UIColor blackColor\];  
    \[self.view addSubview:pageControl\];  
    pageControl.numberOfPages = 5;  
    self.pageControl = pageControl;  
\}  
  
/\*\*  
 \*  添加定时器  
 \*/  
\- (void)addTimer \{  
    // 1.创建定时器

NSTimer \*timer = \[NSTimer scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(nextPage) userInfo:nil repeats:YES\];

// 2.把定时器添加到mainRunLoop(主线程也会抽空处理NSTimer的事件)(如果不添加到mainRunLoop，用户做其他操作的时候，定时器就会停止工作)  
    \[\[NSRunLoop mainRunLoop\] addTimer:timer forMode:NSRunLoopCommonModes\];  
    self.timer = timer;  
\}  
  
/\*\*  
 \*  移除定时器  
 \*/  
\- (void)removeTimer \{  
    // 停止定时器  
    \[self.timer invalidate\];  
    // 清空定时器  
    self.timer = nil;  
\}

/\*\*

\*  显示下一页（保证使用定时器不会把100组都轮播完）

\*/  
\- (void)nextPage \{  
    // 1.马上显示回最中间那组的数据  
    NSIndexPath \*currentIndexPath = \[  
    self resetIndexPath\];  
     
    // 2.计算下一个需要展示的位置（每次都在100组中间组开始）  
    NSInteger nextItem = currentIndexPath.item \+ 1;  
    NSInteger nextSection = currentIndexPath.section;  
    if (nextItem == self.dataSourceArr.count) \{  
        nextItem = 0;  
        nextSection ++;  
    \}  
     
    NSIndexPath \*nextIndexPath = \[NSIndexPath indexPathForItem:nextItem inSection:nextSection\];  
     
    // 3.通过动画滚动到下一个位置  
    \[self.collectionView scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES\];  
     
    // 4.显示页码  
    self.pageControl.currentPage = nextItem;  
\}  
  
/\*\*  
 \*  重置indexPath  
 \*/  
\- (NSIndexPath \*)resetIndexPath \{  
    // 1.当前正在展示的位置  
    NSIndexPath \*currentIndexPath = \[\[self.collectionView indexPathsForVisibleItems\] lastObject\];  
     
    // 马上显示回最中间那组的数据  
    NSIndexPath \*currentIndexPathReset = \[NSIndexPath indexPathForItem:currentIndexPath.item inSection:KGCount / 2\];  
    \[self.collectionView scrollToItemAtIndexPath:currentIndexPathReset atScrollPosition:UICollectionViewScrollPositionLeft animated:NO\];  
    return currentIndexPathReset;  
\}  
  
\#pragma mark - UICollectionViewDataSource  
\- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView \*)collectionView \{  
    return KGCount;  
\}  
  
\- (NSInteger)collectionView:(UICollectionView \*)collectionView numberOfItemsInSection:(NSInteger)section \{  
    return self.dataSourceArr.count;  
\}  
  
\- (UICollectionViewCell \*)collectionView:(UICollectionView \*)collectionView cellForItemAtIndexPath:(NSIndexPath \*)indexPath \{  
    KGNewsCell \*cell = \[collectionView dequeueReusableCellWithReuseIdentifier:cell\_id forIndexPath:indexPath\];  
     
    // 传给cell模型  
    cell.news = self.dataSourceArr\[indexPath.item\];  
     
    return cell;  
\}  
  
\#pragma mark - 监听collectionView滚动  
/\*\*  
 \*  用户开始拖拽collectionView  
 \*/  
\- (void)scrollViewWillBeginDragging:(UIScrollView \*)scrollView \{  
    \[self removeTimer\];  
\}  
  
/\*\*  
 \*  当用户停止拖拽(手指离开)  
 \*/  
\- (void)scrollViewDidEndDecelerating:(UIScrollView \*)scrollView \{  
    \[self addTimer\];  
\}  
  
\- (void)scrollViewDidScroll:(UIScrollView \*)scrollView \{  
    int page = (int)(scrollView.contentOffset.x / scrollView.bounds.size.width + 0.5) % self.dataSourceArr.count;       self.pageControl.currentPage = page;\}- (IBAction)testNSTimer:(UIButton \*)sender \{    for (int i = 0; i < 10; i ++) \{        NSLog(@"测试：如果NSTimer不加入mainRunLoop的情况下，点击button，计时器是否还会工作--%d", i);    \}\}

@end

posted @ 2016-02-17 12:51 [Kingdev][] 阅读( ...) 评论( ...) [编辑][Link 1] 收藏

[UICollectionView]: https://www.cnblogs.com/xiu619544553/p/5194984.html
[Kingdev]: https://www.cnblogs.com/xiu619544553/
[Link 1]: https://i.cnblogs.com/EditPosts.aspx?postid=5194984