IOS scrollView 图片浏览

//
//  ViewController.m
//  0426
//
//  Created by apple on 15/4/26.
//  Copyright (c) 2015年 gense. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()<UIScrollViewDelegate>
{
    UIPageControl * pageControl;

    //定义图片名称集合
    NSMutableArray * arr ;

    //主显示图片view
    UIImageView * mainImageView ;

    //
    UIImageView * otherImageView;

    //定义当前显示索引位置
    int currentImageIndex ;

    UIImage * leftImage ;

    UIImage * rightImage;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    //取得屏幕宽度与高度
    CGFloat width = self.view.frame.size.width;
    CGFloat height = self.view.frame.size.height;

    arr = [NSMutableArray arrayWithCapacity:8];

    //添加滚动图片
    for (int i=0 ;i < 8; i++) {
        [arr addObject:[NSString stringWithFormat:@"0%d.jpg",i+1]];
    }

    currentImageIndex = 0;
    [self setImage];

    //实例化不显示图片
    mainImageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:arr[0]]];

    mainImageView.frame = CGRectMake(width, 0, width, height);
    [_scrollView addSubview:mainImageView];

    otherImageView = [[UIImageView alloc] init];

    [_scrollView addSubview:otherImageView];

    //设置scrollview 滚动区域

    _scrollView.contentSize = CGSizeMake(3 * width, 0);

    //显示中间图片
    _scrollView.contentOffset = CGPointMake(width, 0);

    //隐藏水平滚动格
    _scrollView.showsHorizontalScrollIndicator = NO;

   _scrollView.pagingEnabled  = YES;

    //注册scrollview 的代理对象
    _scrollView.delegate = self;

    //添加分布条
    pageControl = [[UIPageControl alloc]init];

    //设置分页条位置
    pageControl.center = CGPointMake(width/2, height-39);

    pageControl.bounds = CGRectMake(0, 0, width, 30);

    //设置分页条 分页项的color
    pageControl.pageIndicatorTintColor = [UIColor whiteColor];
    pageControl.currentPageIndicatorTintColor = [UIColor blackColor];

    pageControl.numberOfPages = 8;

    pageControl.currentPage = 0;

    //添加change事件

    [pageControl addTarget:self action:@selector(pageControlPageChange:) forControlEvents:UIControlEventValueChanged];

    [_scrollView addSubview:pageControl];

}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    int currentPage =  scrollView.contentOffset.x/scrollView.frame.size.width ;

    if(currentPage == 1)
    {
        return ;
    }

    //向左滑
    if(currentPage == 0)
    {
        if( currentImageIndex == 0)
        {
            currentImageIndex = 7;
        }
        else
        {
            currentImageIndex--;
        }

        mainImageView.image = leftImage;
        _scrollView.contentOffset = CGPointMake(mainImageView.frame.origin.x, 0);

    }
    else if(2 == currentPage) //向右滑
    {
        if(currentImageIndex == 7)
        {
            currentImageIndex = 0;
        }
        else
        {
            currentImageIndex ++;
        }

        mainImageView.image = rightImage;
        _scrollView.contentOffset = CGPointMake(mainImageView.frame.origin.x, 0);
    }

    pageControl.currentPage = currentImageIndex ;

    //NSLog(@"current page index %d",currentImageIndex);

    //重新设置左右图片

    [self  setImage];

}

- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
    NSLog(@"end scrolling Animation");
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    //调整pageControl bounds size x位置
    pageControl.center = CGPointMake( scrollView.contentOffset.x + scrollView.frame.size.width/2, scrollView.frame.size.height-39);

    //得到主显示图片的位置
    CGFloat mainImageX = mainImageView.frame.origin.x;

    //得到滚动offsetX
    CGFloat offsetX = _scrollView.contentOffset.x;

    //向右滚动
    if(offsetX < mainImageX)
    {
        otherImageView.image = leftImage;
        otherImageView.frame = CGRectMake(0, 0, _scrollView.frame.size.width, _scrollView.frame.size.height);
    }
    else //向左滚动
    {
        otherImageView.image = rightImage;
        otherImageView.frame = CGRectMake(mainImageX*2, 0, _scrollView.frame.size.width, _scrollView.frame.size.height);
    }

}

- (void) pageControlPageChange:(UIPageControl *) page
{
    [UIView animateWithDuration:0.5 animations:^{
        _scrollView.contentOffset = CGPointMake(page.currentPage*_scrollView.frame.size.width, 0);
    }];

}

#pragma mark 取得下一张图片
- (void) setImage
{

    if(currentImageIndex == 0)
    {
        leftImage = [UIImage imageNamed:arr[7]];
        rightImage = [UIImage imageNamed:arr[1]];
    }
    else if(currentImageIndex == 7)
    {
        leftImage = [UIImage imageNamed:arr[6]];
        rightImage = [UIImage imageNamed:arr[0]];

    }
    else
    {
        leftImage = [UIImage imageNamed:arr[currentImageIndex-1]];
        rightImage = [UIImage imageNamed:arr[currentImageIndex+1]];
    }
}

@end