iOS 三个imageView实现图片轮播效果

看到很多应用里都有图片的轮播，正好前段时间做的项目中也用到了。

就想到要写一篇关于轮播的文章，来共享一下这个比较好用的图片轮播方法。

适用于轮播图片比较多的情况，希望大家多多评论。

有什么问题也可以提出来一起讨论。 废话不多说，下面直接上代码-------

<pre><code>
#import "ViewController.h"

#define SCREEN_WIDTH [UIScreen mainScreen].bounds.size.width

#define SCREEN_HEIGHT [UIScreen mainScreen].bounds.size.height

@interface ViewController () <UIScrollViewDelegate>

//实例化scrollview

- (void)createScrollView;

//scrollView添加子视图

- (void)addChildViewAboutMyScroll;

//展示

@property (nonatomic,strong) UIScrollView *myScroll;

@end

@implementation ViewController {

  /**总页数*/
  NSInteger _wholePages;
  /**当前页*/
  NSInteger _currentPage;

}

- (void)viewDidLoad {

 [super viewDidLoad];
  
  /**实例化scrollview*/
  [self createScrollView];

  /**scrollview添加子视图*/
  [self addChildViewAboutMyScroll];

}

//实例化scrollview

- (void)createScrollView {

self.myScroll = [[UIScrollView alloc] initWithFrame:self.view.bounds];

  /**打开按页滚动*/
  self.myScroll.pagingEnabled = YES;
  /**设置代理*/
  self.myScroll.delegate = self;
  /**初始化总页数与当前显示页*/
  _wholePages = 6;
  _currentPage = 1;
  /**设置起始显示点*/
  self.myScroll.contentOffset = CGPointMake(_currentPage * SCREEN_WIDTH, 0);
  /**设置可滚动的最大大小*/
  self.myScroll.contentSize = CGSizeMake(3 * SCREEN_WIDTH, 0);
  /**添加到view上*/
  [self.view addSubview:self.myScroll];

}

//scrollView添加子视图

- (void)addChildViewAboutMyScroll {

for (int i = 0; i < 3; i++) {

    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(i*SCREEN_WIDTH, 0, SCREEN_WIDTH, SCREEN_HEIGHT)];
    
    /**初始化显示三张图片*/
    imageView.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:[NSString stringWithFormat:@"海贼%02d",i] ofType:@"jpg"]];
    
    [self.myScroll addSubview:imageView];
  }

}

//数据刷新

- (void)refreshData {

  [self updateSubImageView:(_currentPage - 1) with:0];
  [self updateSubImageView:_currentPage with:1];
  [self updateSubImageView:(_currentPage + 1) with:2];

}

/**

abstact：根据传入数据修改相对应子视图

imageName：拼接图片名字

index：子视图下标

*/

- (void)updateSubImageView:(NSInteger)imageName with:(NSInteger)index {

  UIImage *image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:[NSString stringWithFormat:@"海贼%02ld",((imageName + _wholePages) % _wholePages) ] ofType:@"jpg"]];

  UIImageView *imageView = self.myScroll.subviews[index];
  /**修改子视图显示图片*/
  imageView.image = image;

}

#pragma mark ------------scrollview协议相关-----------

//滚动视图停止滚动

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {

  /**计算当前显示的是第几页*/
  NSInteger subViewIndex = scrollView.contentOffset.x / SCREEN_WIDTH;
  switch (subViewIndex) {
      case 0:
      {
          _currentPage = ((_currentPage - 1) % _wholePages);
          [self refreshData];
      }
          break;
        
      case 2:
      {
          _currentPage = ((_currentPage + 1) % _wholePages);
          [self refreshData];
      }
          break;
    
      default:
          break;
  }
  /**刷新ContentOffSet*/
  [self.myScroll setContentOffset:CGPointMake(SCREEN_WIDTH, 0) animated:NO];

}

</pre></code>