ios UIScrollView 循环滑动

demo地址 1: http://download.csdn.net/detail/take8619702/4767432
demo地址 2: http://download.csdn.net/detail/take8619702/4767443
demo地址 3: http://download.csdn.net/detail/take8619702/4767459
1.普通分页滑动

myScrollView = [[UIScrollViewalloc]initWithFrame:CGRectMake(0,0,320,460)];
[myScrollViewsetContentSize:CGSizeMake(pageWidth*3,460)];
[myScrollViewsetBackgroundColor:[UIColorscrollViewTexturedBackgroundColor]];
[myScrollViewsetPagingEnabled:YES];//当此属性设置为YES时，才能自动分页
[self.viewaddSubview:myScrollView];
2.循环滑动

实现UIScrollViewDelegate代理: [myScrollViewsetDelegate:self];
初始化时，myScrollView 置于中间: [myScrollView setContentOffset:CGPointMake(pageWidth, 0)]

滑动结束之后，回到中间: [myScrollViewsetContentOffset:CGPointMake(pageWidth,0)];
代理方法:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.x <=0) {
[scrollView setContentOffset:CGPointMake(pageWidth,0)];
}
if (scrollView.contentOffset.x >=2*pageWidth) {
[scrollView setContentOffset:CGPointMake(pageWidth,0)];
}

}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
[scrollView setContentOffset:CGPointMake(pageWidth,0)animated:YES];
}

3.加上图片查看效果

这两句的位置不能交换

[selfloadScrollViewSubViews];
[myScrollViewsetContentOffset:CGPointMake(pageWidth,0)];

- (void)loadScrollViewSubViews
{
imageView1 = [[UIImageViewalloc]initWithImage:[UIImageimageNamed:@"1.jpg"]];
imageView2 = [[UIImageViewalloc]initWithImage:[UIImageimageNamed:@"2.jpg"]];
imageView3 = [[UIImageViewalloc]initWithImage:[UIImageimageNamed:@"3.jpg"]];

[imageView1 setFrame:CGRectMake( 0,0,
pageWidth,460)];
[imageView2 setFrame:CGRectMake( pageWidth,0,pageWidth,460)];
[imageView3 setFrame:CGRectMake(2*pageWidth,0,pageWidth,460)];

[myScrollView addSubview:imageView1];
[myScrollView addSubview:imageView2];
[myScrollView addSubview:imageView3];
}
4.循环效果并未出现，还要加上交换图片的代码

- (void)previousImageViewWithImage
{
UIImage * temp = [imageView1.imageretain];
imageView1.image =imageView2.image;
imageView2.image =imageView3.image;
imageView3.image = temp;
[temp release];
}

- (void)nextImageViewWithImage
{
UIImage * temp = [imageView3.imageretain];
imageView3.image =imageView2.image;
imageView2.image =imageView1.image;
imageView1.image = temp;
[temp release];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.x <=0) {
currentImageCount--;
[selfpreviousImageViewWithImage];
[scrollView setContentOffset:CGPointMake(pageWidth,0)];
}
if (scrollView.contentOffset.x >=2*pageWidth) {
currentImageCount++;
[selfnextImageViewWithImage];
[scrollView setContentOffset:CGPointMake(pageWidth,0)];
}

}

5.完美的ScrollView循环
为什么UIImage * temp = [imageView3.image retain];在此处需要retain，如果不加此句，按home键之后，再回到程序滑动，程序会crash。

感谢Eric yang（对于此问题的解答）

为了显示效果，去掉进度条。

进阶一：

1.知道当前所指向图片

给程序增加计数器，指向当前图片。

int currentImageCount;
初始化为33333331，跟上面的第2点同步。（为了取模3的值，所以不是1，而是33331，随便几个3）

2.如果向后滑动，currentImageCount++;
如果向前滑动，currentImageCount--;

3.为了防止回滑多次，乱成图片，程序混乱
所以还需要增加判断，在：

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

if (currentImageCount == 0) {
currentImageCount = 33333330;
}

4.给myScrollView一个tap事件，点击图片，弹出当前图片计数（理论计数）

- (void)addTapEventOnMyScrollView
{
tap = [[UITapGestureRecognizeralloc]initWithTarget:selfaction:@selector(tapEvent)];
[myScrollViewaddGestureRecognizer:tap];
}

- (void)tapEvent
{
NSString * strMsg = [NSStringstringWithFormat:@"当前图片理论计数:%i",curentImage];
UIAlertView * alert = [[UIAlertViewalloc]initWithTitle:@"图片计数"
message:strMsg delegate:nilcancelButtonTitle:@"确定"otherButtonTitles:nil];
[alert show];
[alert release];
}

5.增加一个pageControl,直观显示当前滑动

- (void)addMyPageControl
{
myPageControl = [[UIPageControlalloc]initWithFrame:CGRectMake(110,420,100,20)];
[myPageControlsetNumberOfPages:3];
[myPageControl
setCurrentPage:curentImage];
[self.viewaddSubview:myPageControl];
}

进阶二：
1.增加定时器，图片自动滑动

- (void)addAutoTimer
{
myAutoTimer = [NSTimerscheduledTimerWithTimeInterval:5.0target:selfselector:@selector(autoChangeScrollView)userInfo:nilrepeats:YES];
}
- (void)autoChangeScrollView
{
[myScrollViewsetContentOffset:CGPointMake(2*pageWidth,0)animated:YES];
}
2.为了pageControl，与tap事件连接，修攺autoChangeScrollView

- (void)autoChangeScrollView
{
[myScrollViewsetContentOffset:CGPointMake(2*pageWidth,0)animated:YES];
}
3.开始手动滑动时，停止定时器，手动滑动结束后停止定时器

- (void)stopAutoTimer
{
if (myAutoTimer) {
[myAutoTimer invalidate];
myAutoTimer = nil;
}
}

- (void)restartAutoTimer
{
if (!myAutoTimer) {
[self addAutoTimer];
}
}

4.如果用户向后滑动，则自动向后滑动。如果用户向前滑动，则自动向前滑动。增加滑动方向布尔

BOOL isGoBefor;
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.x <=0) {
isGoBefor = YES;
}
if (scrollView.contentOffset.x >=2*pageWidth) {
isGoBefor = NO;
}

}

自动切换函数

- (void)autoChangeScrollView
{
if (isGoBefor) {
[myScrollViewsetContentOffset:CGPointMake(0,0)animated:YES];
} else {
[myScrollViewsetContentOffset:CGPointMake(2*pageWidth,0)animated:YES];
}
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.x <=0) {
isGoBefor = YES;
currentImageCount--;

curentImage =
currentImageCount%3;
//----------------------------------------------------------------------------------------------增加PageControl直观显示当前滑动位置
[myPageControl
setCurrentPage:curentImage];

[selfpreviousImageViewWithImage];
[scrollView setContentOffset:CGPointMake(pageWidth,0)];
}
if (scrollView.contentOffset.x >=2*pageWidth) {
isGoBefor = NO;
currentImageCount++;

curentImage =
currentImageCount%3;
//----------------------------------------------------------------------------------------------增加PageControl直观显示当前滑动位置
[myPageControl
setCurrentPage:curentImage];

[selfnextImageViewWithImage];
[scrollView setContentOffset:CGPointMake(pageWidth,0)];
}
}