iOS scrollview实现三屏复用循环广告

NSArray *imageArr = [[NSArray alloc]initWithObjects:@"banner_理财.jpg",@"banner_惠普",@"banner_炒股", nil];

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

    UIImage *cirImage1 = [UIImage imageNamed:imageArr[i]];

    [cirScrollView.imageArray addObject:cirImage1];

  }

#import <UIKit/UIKit.h>

@interface CirculateScrollview : UIView

@property (nonatomic,strong)NSMutableArray *imageArray;//图片数组
@property (nonatomic,strong)UIScrollView *circulateScrollView;//广告

/*
 三屏复用广告
 适用范围:网络请求或固定本地的广告图片
    适用所有数量广告，广告>=2时自动采用三屏复用技术
 使用方法:例
 在需要添加广告的控制器里面
 
 CirculateScrollview *cview = [[CirculateScrollview alloc]initWithFrame:CGRectMake(0, 20, 320, 200)];
 for (int i=0; i<3; i  ) {
 UIImage *image = [UIImage imageNamed:@"旅行图1"];//传进图片名字方式
 //UIImage *image = UIImage imageWithData:data];//传进data数据图片方式将服务器请求到的data数据图片转换成image形式再传输
 [cview.imageArray addObject:image];
 }
 [self.view addSubview:cview];
 
 */


/*
 图片转换NSData方法
 测试可用
 NSData * data = UIImageJPEGRepresentation(image, 1);
 */

@end

#define ViewWidth self.frame.size.width
#define ViewHeight self.frame.size.height
#define AllImageCount self.imageArray.count-1

@interface CirculateScrollview()<UIScrollViewDelegate>
{
  NSInteger endImageCount;//左边图片
  NSInteger oneImageCount;//中间图片[当前看到的图片]
  NSInteger secondImageCount;//右边图片
}
@property (nonatomic,strong)UIImageView *endImageView;
@property (nonatomic,strong)UIImageView *oneImageView;
@property (nonatomic,strong)UIImageView *secondImageView;
@property (nonatomic,strong)UIPageControl *pageCtl;

@end

@implementation CirculateScrollview


-(id)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self) {
    
  }
  return self;
}

-(NSMutableArray *)imageArray
{
  if (!_imageArray) {
    _imageArray = [[NSMutableArray alloc]init];
  }
  return _imageArray;
}

- (void)drawRect:(CGRect)rect {
  self.circulateScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, ViewWidth, ViewHeight)];
  
  endImageCount = self.imageArray.count-1;
  oneImageCount = 0;
  secondImageCount = 1;
  
  self.circulateScrollView.showsHorizontalScrollIndicator = NO;
  self.circulateScrollView.pagingEnabled = YES;
  self.circulateScrollView.delegate = self;
  self.circulateScrollView.bounces = NO;
  
  self.circulateScrollView.contentOffset = CGPointMake(ViewWidth, 0);
  
  self.backgroundColor = [UIColor whiteColor];
  
  if (!self.imageArray.count) {
    NSLog(@"图片数组为空");
    return;
  }
  
  
  //若广告数量少于2张则不采用三屏复用技术
  if (self.imageArray.count<=1){
    self.circulateScrollView.contentSize = CGSizeMake(ViewWidth, ViewHeight);
    
    self.endImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, ViewWidth, ViewHeight)];
    self.endImageView.image = self.imageArray[endImageCount];
    [self.circulateScrollView addSubview:self.endImageView];
    [self addSubview:self.circulateScrollView];
    
  }else{
    self.circulateScrollView.contentSize = CGSizeMake(ViewWidth*3, ViewHeight);
    
    //左
    self.endImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, ViewWidth, ViewHeight)];
    self.endImageView.image = self.imageArray[endImageCount];
    [self.circulateScrollView addSubview:self.endImageView];
    //中
    self.oneImageView = [[UIImageView alloc]initWithFrame:CGRectMake(ViewWidth, 0, ViewWidth, ViewHeight)];
    self.oneImageView.image = self.imageArray[oneImageCount];
    [self.circulateScrollView addSubview:self.oneImageView];
    //右
    self.secondImageView = [[UIImageView alloc]initWithFrame:CGRectMake(ViewWidth*2, 0, ViewWidth, ViewHeight)];
    self.secondImageView.image = self.imageArray[secondImageCount];
    [self.circulateScrollView addSubview:self.secondImageView];
    
    
    [self addSubview:self.circulateScrollView];
    [self pageNumControl];
  }

}
//添加页符
-(void)pageNumControl
{
  self.pageCtl = [[UIPageControl alloc]initWithFrame:CGRectMake(0, ViewHeight-20, ViewWidth, 20)];
  self.pageCtl.backgroundColor = [UIColor lightGrayColor];
  self.pageCtl.currentPageIndicatorTintColor = [UIColor greenColor];
  self.pageCtl.pageIndicatorTintColor = [UIColor whiteColor];
  self.pageCtl.alpha = 0.7;
  self.pageCtl.numberOfPages = AllImageCount 1;
  [self addSubview:self.pageCtl];
}

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
  if (scrollView.contentOffset.x == 0) {
    endImageCount--;
    oneImageCount--;
    secondImageCount--;
    if (endImageCount<0) {
      endImageCount = AllImageCount;
    }else if (oneImageCount<0){
      oneImageCount = AllImageCount;
    }
    //适配2张图片
    if (secondImageCount<0){
      secondImageCount = AllImageCount;
    }
    //NSLog(@"endImageCount=%ld oneImageCount=%ld secondImageCount=%ld",endImageCount,oneImageCount,secondImageCount);
    
  }else if(scrollView.contentOffset.x == ViewWidth*2){
    endImageCount  ;
    oneImageCount  ;
    secondImageCount  ;
    if (endImageCount>AllImageCount) {
      endImageCount = 0;
    }else if (oneImageCount>AllImageCount){
      oneImageCount = 0;
    }
    //适配2张图片
    if (secondImageCount>AllImageCount){
      secondImageCount = 0;
    }
  }
  //重新加载显示当前位置的图片
  scrollView.contentOffset = CGPointMake(ViewWidth, 0);
  self.endImageView.image = self.imageArray[endImageCount];
  self.oneImageView.image = self.imageArray[oneImageCount];
  self.secondImageView.image = self.imageArray[secondImageCount];
  self.pageCtl.currentPage = oneImageCount;
}

@end