使用UIScrollView和UIPageControl做一个能够用手势来切换图片的效果

利用UIScrollView的滚动效果来实现，先上图:



实现过程是：在viewController里先增加UIScrollView和UIPageControl:

-(void) loadView {
[super loadView];
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 320,480)];
UIPageControl* pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(0, 438, 320, 42)];
self.scrollView = scrollView;
self.pageControl = pageControl;
self.pageControl.opaque = 1;
[self.pageControl addTarget:self action:@selector(changePage:) forControlEvents:UIControlEventValueChanged];

[self.view addSubview:self.scrollView];
[self.view addSubview:self.pageControl];

}

然后来初始化UIScrollView:

- (void)viewDidLoad
{
[super viewDidLoad];

self.contentList = [NSArray arrayWithObjects:@"1",@"2",@"3",@"4",@"5", nil];
NSMutableArray* controllers = [[NSMutableArray alloc] init];
for (unsigned i = 0 ; i < kNumberOfPages; i++) {
[controllers addObject:[NSNull null]];
}

self.viewControllers = controllers;
self.scrollView.pagingEnabled = YES;

//contentSize是内容的宽度
self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width*kNumberOfPages,
self.scrollView.frame.size.height);

self.scrollView.showsHorizontalScrollIndicator = NO;
self.scrollView.showsVerticalScrollIndicator = NO;
self.scrollView.scrollsToTop = NO;
self.scrollView.delegate = self;

self.pageControl.numberOfPages = kNumberOfPages;
self.pageControl.currentPage = 0;

[self loadScrollViewWithPage:0];
[self loadScrollViewWithPage:1];
// Do any additional setup after loading the view.
}

//UserImageViewController里仅仅有一个UIImageView
-(void) loadScrollViewWithPage:(int)page{
if (page < 0) {
return;
}else if(page >= kNumberOfPages) {
//do some thing,like jump to other screen

CalendarViewExample* calendarView = [[CalendarViewExample alloc] init];
[self presentViewController:calendarView animated:YES completion:^{}];
return;
}

UserImageViewController* controller = [self.viewControllers objectAtIndex:page];
if ((NSNull*)controller == [NSNull null]) {
controller = [[UserImageViewController alloc] init];
[self.viewControllers replaceObjectAtIndex:page withObject:controller];
}

if (controller.view.superview == nil) {
CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
controller.view.frame = frame;
[self.scrollView addSubview:controller.view];

NSString* name =[self.contentList objectAtIndex:page];
NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"jpg"];
controller.numberImage.image = [UIImage imageWithContentsOfFile:path];

}
}

假设用手指来滚动的时候:

-(void) scrollViewDidScroll:(UIScrollView *)scrollView{
if (pageControlUsed) {

return;
}

CGFloat pageWidth = scrollView.frame.size.width;
//page表示当前滚动哪一页的标识
int page = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth)+1;

self.pageControl.currentPage = page;

[self loadScrollViewWithPage:page-1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page+1];

}

-(void) scrollViewWillBeginDecelerating:(UIScrollView *)scrollView {
pageControlUsed = NO;
}

-(void) scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
pageControlUsed = NO;
}

然后假设切换到下一页：

-(void) changePage:(id)sender{
int page = self.pageControl.currentPage;
NSLog(@"chanepage page=%d",page);

[self loadScrollViewWithPage:page-1];
[self loadScrollViewWithPage:page];

CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width*page;
frame.origin.y = 0;
[self.scrollView scrollRectToVisible:frame animated:YES];

pageControlUsed = YES;
}

代码能够在http://download.csdn.net/detail/baidu_nod/7547659下载