UIScrollView和UIPageControl的使用（实现图片的循环滚动）

第一、UIScrollView的基本概念

 

是一个可以选择滑动的视图，用于显示更多的内容，可以通过手势放大或者缩小显示更多的内容。

 

有两个子类一个是UITableView，另一个是UITextView

 

第二、基本属性：

 

    scrollView=[[[UIScrollViewalloc] initWithFrame:CGRectMake(0,0, 320,250)] autorelease];

 

    scrollView.backgroundColor=[UIColorredColor];

 

    //设置内容的大小

 

    scrollView.contentSize=CGSizeMake(320*4,250);

 

    //当超出边界时表示是否可以反弹

 

    scrollView.bounces=YES;

 

    //是否分页

 

    scrollView.pagingEnabled=YES;

 

    //是否滚动

 

    scrollView.scrollEnabled=YES;

 

    //是否显示边界

 

    scrollView.showsHorizontalScrollIndicator=YES;

 

    //设置indicator的风格

 

    scrollView.indicatorStyle=UIScrollViewIndicatorStyleWhite;

 

#import <UIKit/UIKit.h>
#define WIDTH self.view.bounds.size.width
#define HEIGHT self.view.bounds.size.height
@interface ViewController : UIViewController<UIScrollViewDelegate>
@property(strong,nonatomic) UIScrollView *scollView;
@property(strong,nonatomic) UIPageControl *pageControl;
@property(strong,nonatomic) NSMutableArray *imageArray;//存储图片的集合
@property(assign,nonatomic) int currentPage;//当前页码
@property(strong,nonatomic) UIImageView *firstImage;//第一张图片
@property(nonatomic,strong) UIImageView * secondImage;//第二张图片
@property(nonatomic,strong) UIImageView * thirdImage;//第三张图片
@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //设置每张视图的大小
    self.scollView=[[UIScrollView alloc] initWithFrame:CGRectMake(0, 30, WIDTH, (HEIGHT-30)/2)];
    self.scollView.backgroundColor=[UIColor grayColor];
    //设置内容面板有几张
    self.scollView.contentSize=CGSizeMake(WIDTH*3, 0);
    //设置分页
    self.scollView.pagingEnabled=YES;
    //指定代理
    self.scollView.delegate=self;
    //隐藏滚动条
    self.scollView.showsHorizontalScrollIndicator=NO;
    [self.view addSubview:self.scollView];
    
    //设置分页的位置
    self.pageControl=[[UIPageControl alloc] initWithFrame:CGRectMake(WIDTH-100, HEIGHT/2-30, 100, 40)];
    //分页
    self.pageControl.numberOfPages=4;
    //设置当前页
    self.pageControl.currentPage=0;
    //指定页码颜色
    self.pageControl.currentPageIndicatorTintColor=[UIColor redColor];
    self.pageControl.pageIndicatorTintColor=[UIColor greenColor];
    [self.view addSubview:self.pageControl];
    
    //初始化存储图片的集合
    self.imageArray=[NSMutableArray arrayWithCapacity:4];
    for (int i=1; i<5; i++) {
        UIImage *image=[UIImage imageNamed:[NSString stringWithFormat:@"%d",i]];
        [self.imageArray addObject:image];
    }
    NSLog(@"%@",self.imageArray);
    self.firstImage=[[UIImageView alloc] init];
    self.secondImage=[[UIImageView alloc] init];
    self.thirdImage=[[UIImageView alloc] init];
    //当前页码为0
    self.currentPage=0;
    [self reloadImage];
    
}

-(void)reloadImage
{
    //第一种情况 第一页
    if (self.currentPage==0) {
        self.firstImage.image=[self.imageArray lastObject];
        self.secondImage.image=[self.imageArray objectAtIndex:self.currentPage];
        self.thirdImage.image=[self.imageArray objectAtIndex:self.currentPage+1];
    }else if(self.currentPage==self.imageArray.count-1)
    {
       //第二种情况
        self.firstImage.image=[self.imageArray objectAtIndex:self.currentPage-1];
        self.secondImage.image=[self.imageArray objectAtIndex:self.currentPage];
        self.thirdImage.image=[self.imageArray objectAtIndex:0];
    }else
    {
       //第三种情况
        self.firstImage.image=[self.imageArray objectAtIndex:self.currentPage-1];
        self.secondImage.image=[self.imageArray objectAtIndex:self.currentPage];
        self.thirdImage.image=[self.imageArray objectAtIndex:self.currentPage+1];
    }
    
    self.firstImage.frame=CGRectMake(0, 0, WIDTH, (HEIGHT-30)/2);
    self.secondImage.frame=CGRectMake(WIDTH, 0, WIDTH, (HEIGHT-30)/2);
    self.thirdImage.frame=CGRectMake(WIDTH*2, 0, WIDTH, (HEIGHT-30)/2);
    
    [self.scollView addSubview:self.firstImage];
    [self.scollView addSubview:self.secondImage];
    [self.scollView addSubview:self.thirdImage];
    
    self.scollView.contentOffset=CGPointMake(WIDTH, 0);
}

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    float x=self.scollView.contentOffset.x;
    //向左翻
    if (x<0||x==0) {
        if (self.currentPage==0) {
            self.currentPage=(int)self.imageArray.count-1;
        }else
        {
            self.currentPage--;
        }
    }
    //向右
    if (x>WIDTH*2||x==WIDTH*2) {
        if (self.currentPage==(int)self.imageArray.count-1) {
            self.currentPage=0;
        }else
        {
            self.currentPage++;
        }
    }
    self.pageControl.currentPage=self.currentPage;
    [self reloadImage];
    
}