UIScrollView现实自动循环滚动

  1 #import "RootViewController.h"
  2 
  3 #define width [UIScreen mainScreen].bounds.size.width
  4 #define heigthY 150
  5 #define scrollTime 1
  6 
  7 @interface RootViewController ()<UIScrollViewDelegate>
  8 {
  9     UIScrollView *_scrollView;
 10     NSMutableArray *imageArray;
 11     UIPageControl *pageControl;
 12 }
 13 @end
 14 
 15 @implementation RootViewController
 16 
 17 - (void)dealloc
 18 {
 19     imageArray = nil;
 20     [super dealloc];
 21 }
 22 
 23 - (void)loadView
 24 {
 25     [super loadView];
 26     _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, width, heigthY)];
 27     _scrollView.pagingEnabled = YES;
 28     _scrollView.delegate = self;
 29     // 开始时选中第二个图片  图片的布局[3-1-2-3-1]
 30     _scrollView.contentOffset = CGPointMake(width, 0);
 31     // 隐藏水平滚动条
 32     _scrollView.showsHorizontalScrollIndicator = NO;
 33     
 34     pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(width - 100,heigthY - 50, 100, 50)];
 35     // 设置pageControl不支持用户操作
 36     pageControl.userInteractionEnabled = NO;
 37     pageControl.currentPageIndicatorTintColor = [UIColor redColor];
 38     pageControl.pageIndicatorTintColor = [UIColor greenColor];
 39     [self.view addSubview:_scrollView];
 40     [self.view addSubview:pageControl];
 41     [_scrollView release];
 42     [pageControl release];
 43     
 44 }
 45 
 46 - (void)viewDidLoad {
 47     [super viewDidLoad];
 48     imageArray = [[NSMutableArray alloc] init];
 49     NSArray *tempArray = @[@"1-3.jpg",@"1-1.jpg",@"1-2.jpg",@"1-3.jpg",@"1-1.jpg"];
 50     [imageArray addObjectsFromArray:tempArray];
 51     // 根据imageArray的数量设置_scrollView的内容大小
 52     _scrollView.contentSize = CGSizeMake(width * imageArray.count, heigthY);
 53     pageControl.numberOfPages = imageArray.count - 2;
 54     // 给_scrollView添加图片
 55     [self addImagesWithScrollView];
 56     
 57     // 添加定时器
 58     NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:scrollTime target:self selector:@selector(automateScroll) userInfo:nil repeats:YES];
 59 }
 60 
 61 // 每隔scrollTime秒就滚动一次
 62 - (void)automateScroll
 63 {
 64     // 因为开始时出现的图片是imageArray中的第二张图片，后面求余后还加1，使得contentOffset为2*width
 65     static int contentOffsetX = 1;
 66     // 为了偏移量始终在(1 至 imageArray.count-2)*width中,((contentOffsetX % (imageArray.count - 2))求余得到的数值在 0~imageArray.count-3中, + 1后让数值保持在 1 至 imageArray.count-2 中
 67     _scrollView.contentOffset = CGPointMake(((contentOffsetX % (imageArray.count - 2)) + 1) *width, 0);
 68     contentOffsetX ++;
 69     NSLog(@"==%d",contentOffsetX);
 70 }
 71 /**
 72  *  给scrollView添加图片
 73  */
 74 - (void)addImagesWithScrollView
 75 {
 76     for (int i = 0; i < imageArray.count; i++) {
 77         UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:imageArray[i]]];
 78         imageView.frame = CGRectMake(i * width, 0, width, heigthY);
 79         [_scrollView addSubview:imageView];
 80         [imageView release];
 81     }
 82 }
 83 
 84 //#pragma mark - UIScrollViewDelegate的方法
 85 - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
 86 {
 87     int imageIndex = scrollView.contentOffset.x / width;
 88     if (imageIndex == 0) {
 89         // 滚到第一张图片时，就跳转到倒数第二张图片
 90         [_scrollView scrollRectToVisible:CGRectMake((imageArray.count - 2)*width, 0, width, heigthY) animated:NO];
 91     }else if (imageIndex == imageArray.count - 1){
 92         // 滚动到最后一张图片时，就跳转到第二张图片
 93         [_scrollView scrollRectToVisible:CGRectMake(width, 0, width, heigthY) animated:NO];
 94     }
 95 }
 96 
 97 /**
 98  *  设置pageControl的当前页
 99  */
100 - (void)scrollViewDidScroll:(UIScrollView *)scrollView
101 {
102     // 加0.5是为了用户体验好些，滑动过程中哪张图片占优就显示占优图片对应的下标
103     int imageIndex = scrollView.contentOffset.x / width + 0.5;
104     if (imageIndex == 0) {
105         // 设置相应的下标（使之减1后与pageControl的下标相对应）
106         imageIndex = (int)imageArray.count - 1;
107     }else if (imageIndex == imageArray.count - 1){
108         // 设置相应的下标（使之减1后与pageControl的下标相对应）
109         imageIndex = 1;
110     }
111     pageControl.currentPage = imageIndex - 1;
112 }
113 
114 @end