iOS实现三屏复用循环广告[从服务器请求的广告]

循环广告我们在开发中已经是熟得不能再熟了，今天整理这篇scrollview三屏复用广告

原理使用scrollview里的三个imageview分别去加载不同的图片，用少量的资源来显示大量或不确定的广告数量，不然如果用普通方法实现广告，难道10个广告用12个scrollview的contentsize去做，岂不是太浪费资源了

代码如下，实现所有数量的循环广告，当广告只有一个时，仅采用单图显示，>=2个广告时，自动采用三屏复用

这里添加图片的方式是通过网络请求，更新服务器上的广告，如果仅使用本地广告，可以将.m文件里的全部图片的添加方式

如：

self.endImageView.image = self.imageArray[endImageCount];
修改为

self.endImageView.image = [UIImage imageNamed:self.imageArray[endImageCount]];
然后在使用该类时，直接将本地图片的名字用数组传过去就行了，如

cview.imageArray = [[NSMutableArray alloc]initWithObjects:@"图片1",@"图片2",@"图片3", nil];

或者不改则使用方法如

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];

}

如果图片给的是地址那可以用imageWithURL这个方法来获取图片

下面讲从服务器获取的广告方式，请求服务器图片及解析这里就不讲了，仅从获取到的data数据后开始

先新建一个类继承UIView，

.h里

 1 #import <UIKit/UIKit.h>
 2 
 3 @interface CirculateScrollview : UIView
 4 
 5 @property (nonatomic,strong)NSMutableArray *imageArray;//图片数组
 6 @property (nonatomic,strong)UIScrollView *circulateScrollView;//广告
 7 
 8 /*
 9  三屏复用广告
10  适用范围:网络请求或固定本地的广告图片
11         适用所有数量广告，广告>=2时自动采用三屏复用技术
12  使用方法:例
13  在需要添加广告的控制器里面
14  
15  CirculateScrollview *cview = [[CirculateScrollview alloc]initWithFrame:CGRectMake(0, 20, 320, 200)];
16  for (int i=0; i<3; i++) {
17  UIImage *image = [UIImage imageNamed:@"旅行图1"];//传进图片名字方式
18  //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
19  [cview.imageArray addObject:image];
20  }
21  [self.view addSubview:cview];
22  
23  */
24 
25 
26 /*
27  图片转换NSData方法
28  测试可用
29  NSData * data = UIImageJPEGRepresentation(image, 1);
30  */
31 
32 @end

.m文件里

实现方法是这三个成员变量，用来读取传输过来的图片在数组中的位置，三屏复用里，我们显示的位置是scrollview的中间位置，左边广告是全部广告的最后一个，中间显示第一个，右边的显示第二个，然后根据左滑成员变量递增，当变量递增到超过广告总数时，重新赋值第一个广告，而右滑递减，递减至－1时，即不在数组范围时，重新赋值广告数组的最后一个

  1 #import "CirculateScrollview.h"
  2 
  3 #define ViewWidth self.frame.size.width
  4 #define ViewHeight self.frame.size.height
  5 #define AllImageCount self.imageArray.count-1
  6 
  7 @interface CirculateScrollview()<UIScrollViewDelegate>
  8 {
  9     NSInteger endImageCount;//左边图片
 10     NSInteger oneImageCount;//中间图片[当前看到的图片]
 11     NSInteger secondImageCount;//右边图片
 12 }
 13 @property (nonatomic,strong)UIImageView *endImageView;
 14 @property (nonatomic,strong)UIImageView *oneImageView;
 15 @property (nonatomic,strong)UIImageView *secondImageView;
 16 @property (nonatomic,strong)UIPageControl *pageCtl;
 17 
 18 @end
 19 
 20 @implementation CirculateScrollview
 21 
 22 
 23 -(id)initWithFrame:(CGRect)frame
 24 {
 25     self = [super initWithFrame:frame];
 26     if (self) {
 27         
 28     }
 29     return self;
 30 }
 31 
 32 -(NSMutableArray *)imageArray
 33 {
 34     if (!_imageArray) {
 35         _imageArray = [[NSMutableArray alloc]init];
 36     }
 37     return _imageArray;
 38 }
 39 
 40 - (void)drawRect:(CGRect)rect {
 41     self.circulateScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, ViewWidth, ViewHeight)];
 42     
 43     endImageCount = self.imageArray.count-1;
 44     oneImageCount = 0;
 45     secondImageCount = 1;
 46     
 47     self.circulateScrollView.showsHorizontalScrollIndicator = NO;
 48     self.circulateScrollView.pagingEnabled = YES;
 49     self.circulateScrollView.delegate = self;
 50     self.circulateScrollView.bounces = NO;
 51     
 52     self.circulateScrollView.contentOffset = CGPointMake(ViewWidth, 0);
 53     
 54     self.backgroundColor = [UIColor whiteColor];
 55     
 56     if (!self.imageArray.count) {
 57         NSLog(@"图片数组为空");
 58         return;
 59     }
 60     
 61     
 62     //若广告数量少于2张则不采用三屏复用技术
 63     if (self.imageArray.count<=1){
 64         self.circulateScrollView.contentSize = CGSizeMake(ViewWidth, ViewHeight);
 65         
 66         self.endImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, ViewWidth, ViewHeight)];
 67         self.endImageView.image = self.imageArray[endImageCount];
 68         [self.circulateScrollView addSubview:self.endImageView];
 69         [self addSubview:self.circulateScrollView];
 70         
 71     }else{
 72         self.circulateScrollView.contentSize = CGSizeMake(ViewWidth*3, ViewHeight);
 73         
 74         //左
 75         self.endImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, ViewWidth, ViewHeight)];
 76         self.endImageView.image = self.imageArray[endImageCount];
 77         [self.circulateScrollView addSubview:self.endImageView];
 78         //中
 79         self.oneImageView = [[UIImageView alloc]initWithFrame:CGRectMake(ViewWidth, 0, ViewWidth, ViewHeight)];
 80         self.oneImageView.image = self.imageArray[oneImageCount];
 81         [self.circulateScrollView addSubview:self.oneImageView];
 82         //右
 83         self.secondImageView = [[UIImageView alloc]initWithFrame:CGRectMake(ViewWidth*2, 0, ViewWidth, ViewHeight)];
 84         self.secondImageView.image = self.imageArray[secondImageCount];
 85         [self.circulateScrollView addSubview:self.secondImageView];
 86         
 87         
 88         [self addSubview:self.circulateScrollView];
 89         [self pageNumControl];
 90     }
 91 
 92 }
 93 //添加页符
 94 -(void)pageNumControl
 95 {
 96     self.pageCtl = [[UIPageControl alloc]initWithFrame:CGRectMake(0, ViewHeight-20, ViewWidth, 20)];
 97     self.pageCtl.backgroundColor = [UIColor lightGrayColor];
 98     self.pageCtl.currentPageIndicatorTintColor = [UIColor greenColor];
 99     self.pageCtl.pageIndicatorTintColor = [UIColor whiteColor];
100     self.pageCtl.alpha = 0.7;
101     self.pageCtl.numberOfPages = AllImageCount+1;
102     [self addSubview:self.pageCtl];
103 }
104 
105 -(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
106 {
107     if (scrollView.contentOffset.x == 0) {
108         endImageCount--;
109         oneImageCount--;
110         secondImageCount--;
111         if (endImageCount<0) {
112             endImageCount = AllImageCount;
113         }else if (oneImageCount<0){
114             oneImageCount = AllImageCount;
115         }
116         //适配2张图片
117         if (secondImageCount<0){
118             secondImageCount = AllImageCount;
119         }
120         //NSLog(@"endImageCount=%ld  oneImageCount=%ld  secondImageCount=%ld",endImageCount,oneImageCount,secondImageCount);
121         
122     }else if(scrollView.contentOffset.x == ViewWidth*2){
123         endImageCount++;
124         oneImageCount++;
125         secondImageCount++;
126         if (endImageCount>AllImageCount) {
127             endImageCount = 0;
128         }else if (oneImageCount>AllImageCount){
129             oneImageCount = 0;
130         }
131         //适配2张图片
132         if (secondImageCount>AllImageCount){
133             secondImageCount = 0;
134         }
135     }
136     //重新加载显示当前位置的图片
137     scrollView.contentOffset = CGPointMake(ViewWidth, 0);
138     self.endImageView.image = self.imageArray[endImageCount];
139     self.oneImageView.image = self.imageArray[oneImageCount];
140     self.secondImageView.image = self.imageArray[secondImageCount];
141     self.pageCtl.currentPage = oneImageCount;
142 }
143 
144 @end