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iOS实现图片自动切换效果

    本文实例为大家分享了iOS实现图片自动切换的具体代码,供大家参考,具体内容如下

    
    #import "ViewController.h"
    #define ImageViewCount 5
     
    @interface ViewController ()<UIScrollViewDelegate>
     
    @property (weak, nonatomic) IBOutlet UIScrollView *imageScrollView;
    @property (weak, nonatomic) IBOutlet UIPageControl *imageViewPageControl;
    @property (strong, nonatomic) NSTimer *timer;
    @end
     
    @implementation ViewController
     
    - (void)viewDidLoad {
     [super viewDidLoad];
     
     [self addImageView2ScrollView];
     self.imageScrollView.contentSize = CGSizeMake(self.imageScrollView.frame.size.width * ImageViewCount, 0);
     
     self.imageScrollView.delegate = self;
     self.imageScrollView.pagingEnabled = YES;//UIScrollView支持拖动分页
     self.imageViewPageControl.numberOfPages = ImageViewCount;
     
     [self addScrollTimer];
    }
     
    - (void)rotatePic{
     int currentPageIndex = self.imageViewPageControl.currentPage;
     if(++currentPageIndex == 5){
      currentPageIndex = 0;
     }
     CGFloat offsetX = currentPageIndex * self.imageScrollView.frame.size.width;
     [UIView animateWithDuration:1 animations:^{
      self.imageScrollView.contentOffset = CGPointMake(offsetX, 0);
     }];
    }
     
    /**添加图片到imageScrollView*/
    - (void)addImageView2ScrollView{
     CGFloat imageWidth = self.imageScrollView.frame.size.width;
     CGFloat imageHeight = self.imageScrollView.frame.size.height;
     for(int i = 0;i <= ImageViewCount;i++){
      UIImageView *imageInScroll = [[UIImageView alloc] init];
      imageInScroll.frame = CGRectMake(i * imageWidth, 0, imageWidth, imageHeight);
      imageInScroll.image = [UIImage imageNamed:[NSString stringWithFormat:@"img_%02d",i + 1]];
      [self.imageScrollView addSubview:imageInScroll];
     }
    }
     
    // 正滚动时执行
    - (void)scrollViewDidScroll:(UIScrollView *)scrollView{
     CGFloat offX = self.imageScrollView.contentOffset.x;//(0,0)距离content内部左上顶点的x轴长度
     NSLog(@"~~~~~~~%f ^^^^^^%f", offX, self.imageScrollView.frame.size.width);
     int currentPageIndex = (offX + .5f * self.imageScrollView.frame.size.width) / self.imageScrollView.frame.size.width;
     self.imageViewPageControl.currentPage = currentPageIndex;
    }
     
    - (void)addScrollTimer{
     self.timer = [NSTimer timerWithTimeInterval:2 target:self selector:@selector(rotatePic) userInfo:nil repeats:YES];
     [[NSRunLoop mainRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
    }
     
    - (void)removeScrollTimer{
     [self.timer invalidate];//释放定时器
     self.timer = nil;
    }
     
    // 开始准备滚动时执行 移除定时滚动操作
    - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
     NSLog(@"~~~scrollViewWillBeginDragging");
     [self removeScrollTimer];
    }
     
    // 结束滚动后执行 添加定时滚动操作
    - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
     NSLog(@"~~~scrollViewDidEndDragging");
     [self addScrollTimer];
    }
    @end

    UIScrollView的运用,以上代码中有详细注释,需注意2点:

    1.注意设置contentSize属性。其中contentSize表示scroll内容尺寸大小

    2.注意设置代理UIScrollViewDelegate,才可调用其中的方法

    对于定时器NSTimer的运用需注意

    1.在线程的loop中添加定时器

    2.注意使用完成回收NSTimer

    以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持lingkb。