循环滚动一个UIScrollView

//  testScrollViewViewController.m
//  testScrollView
//  Created by cash on 11-7-4.
//  Copyright 2011年 [email protected]. All rights reserved.
#import "testScrollViewViewController.h"
@implementation testScrollViewViewController
@synthesize scrollView, slideImages;
#define WIDTH_OF_SCROLL_PAGE 320
#define HEIGHT_OF_SCROLL_PAGE 460
#define WIDTH_OF_IMAGE 320
#define HEIGHT_OF_IMAGE 460
#define LEFT_EDGE_OFSET 0
- (void)viewDidLoad {
    scrollView = [[UIScrollView alloc] init];
    CGRect scrollFrame;
    scrollFrame.origin.x = 0;
    scrollFrame.origin.y = 0;  
    scrollFrame.size.width = WIDTH_OF_SCROLL_PAGE;
    scrollFrame.size.height = HEIGHT_OF_SCROLL_PAGE;
    scrollView = [[UIScrollView alloc] initWithFrame:scrollFrame];
    scrollView.bounces = YES;
    scrollView.pagingEnabled = YES;
    scrollView.delegate = self;
    scrollView.userInteractionEnabled = YES;
    slideImages = [[NSMutableArray alloc] init];
    [slideImages addObject:@"IMG_0116.PNG"];
    [slideImages addObject:@"IMG_0118.PNG"];
    [slideImages addObject:@"IMG_0119.PNG"];
    [slideImages addObject:@"main_bg.png"];
    //add the last image first
    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:[slideImages objectAtIndex:([slideImages count]-1)]]]
    imageView.frame = CGRectMake(LEFT_EDGE_OFSET, 0, WIDTH_OF_IMAGE, HEIGHT_OF_IMAGE);
    [scrollView addSubview:imageView];
    [imageView release];
    for (int i = 0;i<[slideImages count];i++) {
        //loop this bit
        UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImageimageNamed:[slideImages objectAtIndex:i]]];
        imageView.frame = CGRectMake((WIDTH_OF_IMAGE * i) + LEFT_EDGE_OFSET + 320, 0, WIDTH_OF_IMAGE, HEIGHT_OF_IMAGE);
        [scrollView addSubview:imageView];
        [imageView release];
    }
    //add the first image at the end
    imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:[slideImagesobjectAtIndex:0]]];
    imageView.frame = CGRectMake((WIDTH_OF_IMAGE * ([slideImages count] + 1)) + LEFT_EDGE_OFSET, 0, WIDTH_OF_IMAGE, HEIGHT_OF_IMAGE);
    [scrollView addSubview:imageView];
    [imageView release];
    [scrollView setContentSize:CGSizeMake(WIDTH_OF_SCROLL_PAGE * ([slideImages count] + 2), HEIGHT_OF_IMAGE)];
    [scrollView setContentOffset:CGPointMake(0, 0)];
    [self.view addSubview:scrollView];
    [self.scrollViewscrollRectToVisible:CGRectMake(WIDTH_OF_IMAGE,0,WIDTH_OF_IMAGE,HEIGHT_OF_IMAGE) animated:NO]; 
    [super viewDidLoad];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    int currentPage = floor((self.scrollView.contentOffset.x - self.scrollView.frame.size.width / ([slideImages count]+2)) / self.scrollView.frame.size.width) + 1;
    if (currentPage==0) {
        //go last but 1 page
        [self.scrollView scrollRectToVisible:CGRectMake(WIDTH_OF_IMAGE * [slideImagescount],0,WIDTH_OF_IMAGE,HEIGHT_OF_IMAGE) animated:NO];
    } else if (currentPage==([slideImages count]+1)) { //如果是最后+1,也就是要开始循环的第一个
        [self.scrollViewscrollRectToVisible:CGRectMake(WIDTH_OF_IMAGE,0,WIDTH_OF_IMAGE,HEIGHT_OF_IMAGE) animated:NO];
    }
}
- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}
- (void)dealloc {
    [scrollView release];
    [slideImages release];
    [super dealloc];
}
@end