#import <UIKit/UIKit.h>@interface MainViewController : UIViewController<UIScrollViewDelegate>
{//上面的scrollviewUIScrollView *scrollView0;UIPageControl *pageControl0;         //页面控制控件    tag 已在xib文件中设置为0NSMutableArray *arrImageViews;       //相当于datasourceBOOL isLoadScrollView0;              //是否加载
    BOOL pageControlUsed;}
@property (nonatomic,retain) IBOutlet UIScrollView *scrollView0;
@property (nonatomic,retain) IBOutlet UIPageControl *pageControl0;
@property BOOL isLoadScrollView0; - (IBAction)changePage:(id)sender;@end

#import "MainViewController.h"static NSUInteger fNumberOfPages = 4;@interface MainViewController (PrivateMethods)
- (void)loadScrollViewWithPage:(int)page;
- (void)scrollViewDidScroll:(UIScrollView *)sender;
@end@implementation MainViewController
@synthesize scrollView0, pageControl0;
@synthesize isLoadScrollView0;- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];if (self) {// Custom initialization
    }return self;
}- (void)viewDidLoad
{[super viewDidLoad];/* 初始化scrollView0相关内容*///获取scrollView0要显示的相关内容
    arrImageViews = [[NSMutableArray alloc]init];for (int i = 0; i < fNumberOfPages; i++) {UIImage *tempImage = [[UIImage alloc]init];NSString *imageName = [NSString stringWithFormat:@"pic0%d.png", i + 1];tempImage = [UIImage imageNamed:imageName];UIImageView *view = [[UIImageView alloc] initWithImage:tempImage];[arrImageViews addObject:view];}// scrollView0 初始化scrollView0.pagingEnabled = YES;scrollView0.contentSize = CGSizeMake(scrollView0.frame.size.width * fNumberOfPages, scrollView0.frame.size.height);scrollView0.showsHorizontalScrollIndicator = NO;scrollView0.showsVerticalScrollIndicator = NO;scrollView0.scrollsToTop = NO;scrollView0.delegate = self;scrollView0.tag = 1000;pageControl0.numberOfPages = fNumberOfPages;pageControl0.currentPage = 0;     //这个只改变了pagecontrol 被选中的位置
    isLoadScrollView0 = YES;//使用如下3句代码 实现默认显示 scrollview 指定的页CGPoint pt = CGPointMake(640, 0);      [scrollView0 setContentOffset:pt];        //设置scrollview 的偏移量[self scrollViewDidScroll:scrollView0];   //模拟scrollview 被滑动
}- (void)viewDidUnload
{[super viewDidUnload];// Release any retained subviews of the main view.// e.g. self.myOutlet = nil;
}- (IBAction)changePage:(id)sender
{if ([sender tag] == 0) {int page = pageControl0.currentPage;// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)[self loadScrollViewWithPage:page - 1];[self loadScrollViewWithPage:page];[self loadScrollViewWithPage:page + 1];// update the scroll view to the appropriate pageCGRect frame = scrollView0.frame;frame.origin.x = frame.size.width * page;frame.origin.y = 0;[scrollView0 scrollRectToVisible:frame animated:YES];// Set the boolean used when scrolls originate from the UIPageControl. See scrollViewDidScroll: above.pageControlUsed = YES;}
}- (void)loadScrollViewWithPage:(int)page
{if (isLoadScrollView0 == YES) {if (page < 0)return;if (page >= fNumberOfPages)return;// 获取数据UIImageView *view = [arrImageViews objectAtIndex:page];CGRect frame = scrollView0.frame;frame.origin.x = frame.size.width * page;frame.origin.y = 0;view.frame = frame;[scrollView0 addSubview:view];}
}- (void)scrollViewDidScroll:(UIScrollView *)sender
{if ([sender tag] == 1000) {//设置加载的对象isLoadScrollView0 = YES;if (pageControlUsed) {return;}// Switch the indicator when more than 50% of the previous/next page is visibleCGFloat pageWidth = scrollView0.frame.size.width;NSLog(@"scrollView0.contentOffset.x  === %f",scrollView0.contentOffset.x );int page = floor((scrollView0.contentOffset.x - pageWidth / 2) / pageWidth) + 1;pageControl0.currentPage = page;[self loadScrollViewWithPage:page - 1];[self loadScrollViewWithPage:page];[self loadScrollViewWithPage:page + 1];}
}// At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{if (scrollView.tag == 1000) {pageControlUsed = NO;}
}// At the end of scroll animation, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{if (scrollView.tag == 1000) {pageControlUsed = NO;}
}- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
//    return (interfaceOrientation == UIInterfaceOrientationPortrait);return NO;
}
@end