自动滚动，自动显示下一个图像

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController
<UIScrollViewDelegate,UIPageViewControllerDelegate>
{
    UIScrollView *imageScrollView;
    UIPageControl *pageControl;
    NSInteger changePage;
    NSTimer *showtimer;
    
}

@end

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    self.title=@"自动滚动，自动显示下一个图像";
    
    //自动切换页面
    showtimer=[NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(changePageNumber) userInfo:nil repeats:YES];
    //加滚动条
    [self addScrollView];
    //加滑动的圆点
    [self addPageControl];

    
    
}
#pragma -mark -functions
//加入滚动条
-(void)addScrollView {
    
    imageScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 100, 320, 120)];
    [imageScrollView setBackgroundColor:[UIColor redColor]];;
    [imageScrollView setContentSize:CGSizeMake(320*4, 120)];
    [imageScrollView setBounces:NO];
    [imageScrollView setDelegate:self];;
    imageScrollView.pagingEnabled = YES;
    imageScrollView.showsHorizontalScrollIndicator = NO;
    imageScrollView.showsVerticalScrollIndicator=NO;
    [self.view addSubview:imageScrollView];
    
    int i = 0;
    for ( i = 0; i <4; i++) {
        UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(320*i, 0, 320, 120)];
        imageView.image=[UIImage imageNamed:[NSString stringWithFormat:@"%i.jpg",i]];
        imageView.tag = 110 + i;
        imageView.userInteractionEnabled=YES;
        [imageScrollView addSubview:imageView];
    }
    
}
//加入白色的滑动条
-(void) addPageControl {
    pageControl = [[UIPageControl alloc]initWithFrame:CGRectMake(145, 190, 100, 40)];
    pageControl.numberOfPages =4;
    pageControl.tag = 101;
    pageControl.currentPage = 0;
    pageControl.backgroundColor=[UIColor clearColor];
    [self.view addSubview:pageControl];
}

#pragma -mark -UIPageViewControllerDelegate
-(void)changePageNumber
{
    pageControl.currentPage=pageControl.currentPage+1;
    if (pageControl.currentPage==3) {
        changePage = changePage+1;
        
    }
    if (changePage==2) {
        pageControl.currentPage=0;
        changePage=0;
    }
    
    [imageScrollView scrollRectToVisible:CGRectMake(pageControl.currentPage * 320.0, 65.0, 320.0, 218.0) animated:YES];
    
}
-(void) tap: (UITapGestureRecognizer*)sender{
    NSLog(@"tap %ld image",(long)pageControl.currentPage);
}

#pragma -mark -UIScrollViewDelegate
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    int current = scrollView.contentOffset.x/320;
    NSLog(@"current:%d",current);
    pageControl.currentPage = current;
    if (pageControl.currentPage==3) {
        changePage = changePage+1;
        
    }
    if (changePage==2) {
        pageControl.currentPage=0;
        [imageScrollView scrollRectToVisible:CGRectMake(pageControl.currentPage * 320.0, 65.0, 320.0, 218.0) animated:YES];
        changePage=0;
    }
    
}