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#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
UICollectionView实现无限轮播
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原文地址：http://www.cnblogs.com/xiu619544553/p/5194984.html
