UIScrollView实现图片轮播器及其无限循环效果

1 #import "YYViewController.h"
2
3 @interface YYViewController () <UIScrollViewDelegate>
4 @property (weak, nonatomic) IBOutlet UIScrollView *scrollview;
5 /**
6 * 页码
7 */
8 @property (weak, nonatomic) IBOutlet UIPageControl *pageControl;
9
10 @property (nonatomic, strong) NSTimer *timer;
11 @end
12
13 @implementation YYViewController
14
15 - (void)viewDidLoad
16 {
17 [super viewDidLoad];
18
19 // 图片的宽
20 CGFloat imageW = self.scrollview.frame.size.width;
21 // CGFloat imageW = 300;
22 // 图片高
23 CGFloat imageH = self.scrollview.frame.size.height;
24 // 图片的Y
25 CGFloat imageY = 0;
26 // 图片中数
27 NSInteger totalCount = 5;
28 // 1.添加5张图片
29 for (int i = 0; i < totalCount; i++) {
30 UIImageView *imageView = [[UIImageView alloc] init];
31 // 图片X
32 CGFloat imageX = i * imageW;
33 // 设置frame
34 imageView.frame = CGRectMake(imageX, imageY, imageW, imageH);
35 // 设置图片
36 NSString *name = [NSString stringWithFormat:@"img_0%d", i + 1];
37 imageView.image = [UIImage imageNamed:name];
38 // 隐藏指示条
39 self.scrollview.showsHorizontalScrollIndicator = NO;
40
41 [self.scrollview addSubview:imageView];
42 }
43
44 // 2.设置scrollview的滚动范围
45 CGFloat contentW = totalCount *imageW;
46 //不允许在垂直方向上进行滚动
47 self.scrollview.contentSize = CGSizeMake(contentW, 0);
48
49 // 3.设置分页
50 self.scrollview.pagingEnabled = YES;
51
52 // 4.监听scrollview的滚动
53 self.scrollview.delegate = self;
54
55 [self addTimer];
56 }
57
58 - (void)nextImage
59 {
60 int page = (int)self.pageControl.currentPage;
61 if (page == 4) {
62 page = 0;
63 }else
64 {
65 page++;
66 }
67
68 // 滚动scrollview
69 CGFloat x = page * self.scrollview.frame.size.width;
70 self.scrollview.contentOffset = CGPointMake(x, 0);
71 }
72
73 // scrollview滚动的时候调用
74 - (void)scrollViewDidScroll:(UIScrollView *)scrollView
75 {
76 NSLog(@"滚动中");
77 // 计算页码
78 // 页码 = (contentoffset.x + scrollView一半宽度)/scrollView宽度
79 CGFloat scrollviewW = scrollView.frame.size.width;
80 CGFloat x = scrollView.contentOffset.x;
81 int page = (x + scrollviewW / 2) / scrollviewW;
82 self.pageControl.currentPage = page;
83 }
84
85 // 开始拖拽的时候调用
86 - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
87 {
88 // 关闭定时器(注意点; 定时器一旦被关闭,无法再开启)
89 // [self.timer invalidate];
90 [self removeTimer];
91 }
92
93 - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
94 {
95 // 开启定时器
96 [self addTimer];
97 }
98
99 /**
100 * 开启定时器
101 */
102 - (void)addTimer{
103
104 self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];
105 106 }
107 /**
108 * 关闭定时器
109 */
110 - (void)removeTimer
111 {
112 [self.timer invalidate];
113 }
114 @end