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关于图片的横向滑动或者iOS APP的图片启动页的横向滑动启动图

• 今天做了一个小的demo，很简单，希望能帮助大家。
  首先先说一下我的思路，使用UICollectionVIew做图片滑动，首先collectionView的layout方式为横向的，然后一个collectionCell一张满屏的图片，通过左右滑动到不同的图片cell，有一个pageControl显示滑动到了哪一张图片。思路很简单，代码也很简单。
• ViewController.h代码如下：
  #import <UIKit/UIKit.h>
  @interface ViewController : UIViewController
  @end
• ViewController.m的代码如下：

#define identifier @"welcomeCell"
//屏幕宽度
#define SCREEN_WIDTH [[UIScreen mainScreen] bounds].size.width
//屏幕高度
#define SCREEN_HEIGHT [[UIScreen mainScreen] bounds].size.height
#import "ViewController.h"
@interface ViewController ()<UIScrollViewDelegate,UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout>
@property (nonatomic, strong)NSMutableArray *imageArray;
@property (nonatomic, assign)Boolean isFullScreen;
@property (nonatomic, strong)UICollectionView *collectionView;
@property (nonatomic, strong)UIPageControl *pageControl;
@property (nonatomic, assign)int currentIndex;
@end

      @implementation ViewController
      - (void)viewDidLoad { [super viewDidLoad];     
            self.imageArray = [NSMutableArray arrayWithArray:@[@"001.jpg",@"002.jpg",@"003.jpg"]];
            [self intiWithCollection];
        }
      - (void)didReceiveMemoryWarning {
          [super didReceiveMemoryWarning];
      }
      - (void)intiWithCollection
      {
            int imageCount = self.imageArray.count;
            UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];
            layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
            layout.itemSize = CGSizeMake(SCREEN_WIDTH, SCREEN_HEIGHT);
            layout.minimumInteritemSpacing = 0.0f;
    
            _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH , SCREEN_HEIGHT) collectionViewLayout:layout];
          _collectionView.backgroundColor = [UIColor clearColor];
          _collectionView.delegate = self;
          _collectionView.dataSource = self;
           _collectionView.pagingEnabled = YES;
          self.collectionView.showsHorizontalScrollIndicator = NO;
          self.collectionView.showsVerticalScrollIndicator = NO;
          [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:identifier];
          self.collectionView.contentSize = CGSizeMake(SCREEN_WIDTH*imageCount, SCREEN_HEIGHT);
          self.collectionView.contentOffset = CGPointMake(0, 0);
          [self.view addSubview:_collectionView];
    
          //pageControl 一直不居中  只能这样设置了
          self.pageControl = [[UIPageControl alloc]initWithFrame:CGRectMake(SCREEN_WIDTH/2, SCREEN_HEIGHT- 60, 40, 40)];
    
          self.pageControl.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;
          self.pageControl.numberOfPages = self.imageArray.count;
          if(self.imageArray.count == 1){
            self.pageControl.alpha = 0;
          }
          self.pageControl.currentPage = 0;
          self.pageControl.pageIndicatorTintColor = [UIColor greenColor];
          self.pageControl.currentPageIndicatorTintColor = [UIColor orangeColor];
          [self.view insertSubview:_pageControl aboveSubview:_collectionView];
      }
        - (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
        {
            return 1;
        }

        - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
      {
        return _imageArray.count;
      }

        - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
        {
          UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
    
          for (UIView *view in cell.contentView.subviews) {
              [view removeFromSuperview];
          }
            NSLog(@"indexPath.row ====>%ld",(long)indexPath.row);
          UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:_imageArray[indexPath.row]]];
          imageView.frame = CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
          [cell.contentView addSubview:imageView];
          return cell;
      }

        - (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
      {
          return UIEdgeInsetsMake(0, 0, 0, 0);
      }

      - (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{
          return 0;
      }

      - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
      {
          return CGSizeMake(SCREEN_WIDTH, SCREEN_HEIGHT);
      }

      - (void)scrollViewDidScroll:(UIScrollView *)scrollView
      {
          //得到每页宽度
          CGFloat pageWidth = scrollView.frame.size.width;
          // 根据当前的x坐标和页宽度计算出当前页数
          _currentIndex = floor((scrollView.contentOffset.x - pageWidth/2)/pageWidth) + 1;
          if(_currentIndex == _imageArray.count-1){
        
          }
          self.pageControl.currentPage = _currentIndex;
        }
      @end  

- MarkDown得使用还不熟练，使用代码块感觉真的不好用-----引入代码真的很辛苦。demo的下载的地址为：<https://github.com/tanghan0328/WelcomeImageCollection>