////  LWTViewController.m//  无限滚动////  Created by apple on 14-7-30.//  Copyright (c) 2014年 lwt. All rights reserved.//#import "LWTViewController.h"#import "LWTNews.h"#import "MJExtension.h"#import "LWTNewsCell.h"#define LWTCellIdentifier @"news"#define LWTMaxSection 100@interface LWTViewController () <UICollectionViewDataSource, UICollectionViewDelegate>@property (weak, nonatomic) IBOutlet UICollectionView *collectionView;@property (nonatomic, strong) NSArray *newses;@property (nonatomic, weak) IBOutlet UIPageControl *pageContol;@property (nonatomic, strong) NSTimer *timer;@end@implementation LWTViewController-(NSArray *)newses{    if (_newses == nil) {        _newses = [LWTNews objectArrayWithFilename:@"newses.plist"];        self.pageContol.numberOfPages = self.newses.count;    }    return _newses;}- (void)viewDidLoad{    [super viewDidLoad];    // 注册cell    [self.collectionView registerNib:[UINib nibWithNibName:@"LWTNewsCell" bundle:nil] forCellWithReuseIdentifier:LWTCellIdentifier];        // 默认显示最中间的那组    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:LWTMaxSection / 2] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];        // 添加定时器    [self addTimer];    }/** *  添加定时器 */- (void)addTimer{    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];    [[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];    self.timer = timer;}/** *  移除定时器 */- (void)stopTimer{    [self.timer invalidate];    self.timer = nil;}- (NSIndexPath *)resetIndexPath{    // 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:LWTMaxSection / 2];    [self.collectionView scrollToItemAtIndexPath:currentIndexPathReset atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];        return currentIndexPathReset;}/** *  下一页 */- (void)nextPage{    // 1.马上显示回最中间那组的数据    NSIndexPath *indexPath = [self resetIndexPath];         // 2.计算出下一个需要展示的位置    NSInteger nextItem = indexPath.item + 1;    NSInteger nextSection = indexPath.section;    if (nextItem >= self.newses.count) {        nextItem = 0;        nextSection++;    }        // 3.通过动画滚动到下一个位置    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:nextItem inSection:nextSection] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];}#pragma mark - UICollectionViewDataSource- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{    return LWTMaxSection;}- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return self.newses.count;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    LWTNewsCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:LWTCellIdentifier forIndexPath:indexPath];    cell.news = self.newses[indexPath.item];    return cell;}#pragma mark  - UICollectionViewDelegate/** *  当用户即将开始拖拽的时候就调用 */- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{    [self stopTimer];}- (void)scrollViewDidScroll:(UIScrollView *)scrollView{    int page = (int)(scrollView.contentOffset.x / scrollView.bounds.size.width + 0.5) % self.newses.count;    self.pageContol.currentPage = page;}/** *  当用户停止拖拽的时候就调用 */- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{    [self addTimer];}@end