UIScrollView自动轮播图

添加定时器，自动播放图片列表

#import "JZScrollViewController.h"

@interface JZScrollViewController () <UIScrollViewDelegate>

@property (nonatomic, strong) UIScrollView * scrollView;
@property (nonatomic, strong) UIPageControl * pageControl;
@property (nonatomic, strong) NSTimer * timer;

@end

@implementation JZScrollViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    [self initScroll];
    [self addImageWithtag:1000];
    [self initpageControl];
    
    [self addTime];
}

//初始化Scroll
- (void)initScroll
{
    UIScrollView * scroll = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)];
    scroll.showsHorizontalScrollIndicator = NO;
    scroll.showsVerticalScrollIndicator = NO;
    scroll.contentSize = CGSizeMake([UIScreen mainScreen].bounds.size.width * 3, 0);
    scroll.pagingEnabled = YES;
    scroll.delegate = self;
    self.scrollView = scroll;
    [self.view addSubview:self.scrollView];
}

//初始化pageControl
- (void)initpageControl
{
    UIPageControl * page = [[UIPageControl alloc] initWithFrame:CGRectMake(([UIScreen mainScreen].bounds.size.width - 200) / 2, 300 - 30, 200, 30)];
    page.numberOfPages = 3;
    page.currentPage = 0;
    page.currentPageIndicatorTintColor = [UIColor blackColor];
    page.pageIndicatorTintColor = [UIColor greenColor];
    page.userInteractionEnabled = NO;
    
    self.pageControl = page;
    [self.view addSubview:page];
}

//添加图片
- (void)addImageWithtag:(NSInteger) tag
{
    for(int i = 0; i < 3; i++){
        NSString * name = [NSString stringWithFormat:@"%d.jpg", i + 1];
        UIImage * image = [UIImage imageNamed:name];
        UIImageView * imageView = [[UIImageView alloc] initWithFrame:CGRectMake(i * [UIScreen mainScreen].bounds.size.width, 100, [UIScreen mainScreen].bounds.size.width, 200)];
        imageView.tag = tag + i;
        imageView.image = image;
        
        [self.scrollView addSubview:imageView];
    }
}

//滚动图片达到轮播图的效果
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat scrollX = self.scrollView.contentOffset.x + [UIScreen mainScreen].bounds.size.width / 2;
    int num = (int)(scrollX / [UIScreen mainScreen].bounds.size.width);
    NSLog(@"%d", num);
    self.pageControl.currentPage = num;
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    //关闭定时器
    [self removeTime];
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    //打开定时器
    [self addTime];
}

//开启定时器
- (void)addTime
{
    self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}

//关闭定时器
- (void)removeTime
{
    [self.timer invalidate];
}

//显示下一张图片
- (void)nextImage
{
    int page = (int)self.pageControl.currentPage;
    if(page == 2){
        page = 0;
    }else{
        page++;
    }
    CGFloat X = page * self.scrollView.frame.size.width;
    self.scrollView.contentOffset = CGPointMake(X, 0);
}

@end