ScrollView 实现循环轮播

Posted 2020-07-19 山水间

  1 #import "MassageViewController.h"
  2 @interface MassageViewController()<UIScrollViewDelegate>
  3 @property (nonatomic,strong) UIScrollView *PicScrollView;
  4 @property (nonatomic,strong) UIPageControl *PicCtr;
  5 @property (nonatomic,strong) NSTimer *timer;
  6 @property (nonatomic,strong) NSMutableArray *picArr;
  7 @property (nonatomic,strong) UIImageView *PicImageView;
  8 @property (nonatomic,strong) UIImageView *lastImageView;
  9 @end
 10 
 11 @implementation MassageViewController
 12 -(NSMutableArray *)picArr{
 13     if (self.picArr==nil) {
 14         _picArr = [NSMutableArray array];
 15     }
 16     return _picArr;
 17 }
 18 
 19 -(void)viewDidLoad{
 20     self.picArr = [self loadImageData];
 21     self.PicScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 150, self.view.frame.size.width, 200)];
 22     _PicScrollView.pagingEnabled = YES;
 23     _PicScrollView.delegate = self;
 24     _PicScrollView.showsHorizontalScrollIndicator = NO;
 25     _PicScrollView.tag = 1000;
 26     _PicScrollView.contentSize = CGSizeMake(self.PicScrollView.width * (_picArr.count), 0);
 27     for (int i =0; i<_picArr.count; i++) {
 28         CGFloat imgX = self.view.frame.size.width * i;
 29         self.PicImageView = [[UIImageView alloc]initWithFrame:CGRectMake(imgX, 0, self.view.frame.size.width, 200)];
 30         _PicImageView.image = [_picArr objectAtIndex:i];
 31         [_PicScrollView addSubview:_PicImageView];
 32     }
 33     CGFloat imgX = CGRectGetWidth(self.view.frame)*_picArr.count;
 34     _lastImageView = [[UIImageView alloc]initWithFrame:CGRectMake(imgX, 0, self.view.frame.size.width, 200)];
 35     _lastImageView.image = [_picArr objectAtIndex:0];
 36     [_PicScrollView addSubview:_lastImageView];
 37     
 38     
 39     [self.view addSubview:_PicScrollView];
 40     self.PicCtr = [[UIPageControl alloc]initWithFrame:CGRectMake((self.PicScrollView.width-150)/2, self.PicScrollView.y+200-40, 150, 30)];
 41     _PicCtr.pageIndicatorTintColor = [UIColor grayColor];
 42     _PicCtr.currentPageIndicatorTintColor = [UIColor redColor];
 43     _PicCtr.numberOfPages = 5;
 44     _PicCtr.currentPage = 0;
 45     [self.view addSubview:_PicCtr];
 46     [self.view bringSubviewToFront:_PicCtr];
 47     
 48     self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(scrollImage) userInfo:nil repeats:YES];
 49     //修改优先级与其他控件一样
 50     //获取当前消息循环对象
 51     NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
 52     //设置优先级
 53     [runLoop addTimer:self.timer forMode:NSRunLoopCommonModes];
 54 }
 55 
 56 -(NSMutableArray *)loadImageData{//加载图片
 57     NSMutableArray *arr = [NSMutableArray array];
 58     for (int i = 0; i<5; i++) {
　　　　　　　　//为了节约内存，建议使用路径加载，注意图片不要放在Assets.xcassets里面，否则读取不到
 59         NSString *imgName = [NSString stringWithFormat:@"%02d.jpg",i+1];//注意.jpg格式，图片格式统一
 60         NSString *imgPath = [[NSBundle mainBundle]pathForResource:imgName ofType:nil];
 61         UIImage *image = [UIImage imageWithContentsOfFile:imgPath];
 62         [arr addObject:image];
 63     }
 64     return arr;
 65 }
 66 
 67 -(UIStatusBarStyle)preferredStatusBarStyle{
 68     return UIStatusBarStyleLightContent;
 69 }
 70 
 71 -(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
 72     //停止计时器
 73     [self.timer invalidate];
 74     self.timer = nil;
 75 }
 76 
 77 -(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
 78     
 79     //r如果放到didscroll里面，每次自动播放都会调用，我们想要手指拖动时才调用，所以放到这里面，每次拖到第几张，白点就点亮
 80     CGFloat offsetX = self.PicScrollView.contentOffset.x + self.PicScrollView.frame.size.width/2;
 81     int index = offsetX/self.PicScrollView.width;
 82     _PicCtr.currentPage = index;
 83 
 84     //重新启用计时器
 85     self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(scrollImage) userInfo:nil repeats:YES];
 86     //修改优先级与其他控件一样
 87     //获取当前消息循环对象
 88     NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
 89     //设置优先级
 90     [runLoop addTimer:self.timer forMode:NSRunLoopCommonModes];
 91 }
 92 
 93 -(void)scrollImage{
 94     //在scrollview后面加一个imageview，和第一个图一样。
 95     float offsetx = _PicScrollView.contentOffset.x;
 96     offsetx += CGRectGetWidth(self.view.frame);
 97     if (offsetx == CGRectGetWidth(self.view.frame)*_picArr.count) {
 98         _PicCtr.currentPage = 0;
 99     }else{
100         _PicCtr.currentPage = offsetx/CGRectGetWidth(self.view.frame);
101     }
102     if (offsetx>CGRectGetWidth(self.view.frame)*_picArr.count) {
103         //直接复制速度很快直接和lastImageView一样，看起来就是循环播放的
104         _PicScrollView.contentOffset= CGPointMake(0, 0);
105         _PicCtr.currentPage = 1;
106         [_PicScrollView setContentOffset:CGPointMake(CGRectGetWidth(self.view.frame), 0)  animated:YES];
107     }else{
108         [_PicScrollView setContentOffset:CGPointMake(offsetx, 0) animated:YES];
109     }
110 }
111 @end