Viewcontroller.m 文件

#import "ViewController.h"

@interface ViewController () <UIScrollViewDelegate>
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;
@property (weak, nonatomic)NSTimer *timer;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    CGFloat scrollViewW = self.scrollView.frame.size.width;
    CGFloat scrollViewH = self.scrollView.frame.size.height;
    int count = 5;
    for (int i = 0; i <= count; i++) {
        NSString *name = [NSString stringWithFormat:@"img_0%d", i+1];
        UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:name]];
        imageView.frame = CGRectMake(i * scrollViewW, 0, scrollViewW, scrollViewH);
        [self.scrollView addSubview:imageView];
    }
    self.scrollView.contentSize = CGSizeMake(scrollViewW * count, 0);
    self.scrollView.showsHorizontalScrollIndicator = NO;
    self.scrollView.pagingEnabled = YES;
    self.scrollView.delegate = self;
    self.pageControl.numberOfPages = count;
    self.pageControl.hidesForSinglePage = YES;
//    if(count <= 1){
//        self.pageControl.hidden = YES;
//    }
    self.pageControl.userInteractionEnabled = NO;
    [self.pageControl setValue:[UIImage imageNamed:@"current"] forKeyPath:@"_currentPageImage"];
    [self.pageControl setValue:[UIImage imageNamed:@"other"] forKey:@"_pageImage"];
    [self startTimer];


}

#pragma mark - 定时器相关的代码
- (void)startTimer
{
    //返回一个自动执行的定时器对象

    self.timer =  [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];


}
- (void)stopTimer
{
    [self.timer invalidate]; //invalidate  使......无效
    self.timer = nil;
}
- (void)nextPage{
    NSInteger page = self.pageControl.currentPage + 1;
    if (page == 5) {
        page = 0;
    }
    [self.scrollView setContentOffset:CGPointMake(page * self.scrollView.frame.size.width, 0)];
}


#pragma mark - UIScrollViewDelegate
//拖拽的时候停止定时器
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    [self stopTimer];
}

//停止拖拽的时候开始定时器
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    [self startTimer];
}

//- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
//{
//    int pageNumber = scrollView.contentOffset.x / scrollView.frame.size.width;
//    self.pageControl.currentPage = pageNumber;
//}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    int pageNumber = scrollView.contentOffset.x / scrollView.frame.size.width+0.5;
    self.pageControl.currentPage = pageNumber;

}
@end