UI028---UIScrollView控件实现图片轮播

UIScrollView控件实现图片轮播

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一、实现效果

实现图片的自动轮播

二、实现代码

storyboard中布局

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     [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
106 }
107 /**
108  *  关闭定时器
109  */
110 - (void)removeTimer
111 {
112     [self.timer invalidate];
113 }
114 @end

提示：以下两个属性已经和storyboard中的控件进行了连线。

@property (weak, nonatomic) IBOutletUIScrollView *scrollview;

@property (weak, nonatomic) IBOutletUIPageControl *pageControl;

补充：定时器NSTimer

定时器 适合用来隔一段时间做一些间隔比较长的操作

NSTimeInterval:多长多件操作一次

target :操作谁

selector : 要操作的方法

userInfo: 传递参数

repeats: 是否重复

self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];